diff --git a/core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/codeGen/CodeGeneratorImpl.kt b/core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/codeGen/CodeGeneratorImpl.kt
index a9b0e94b73..8309cf5237 100644
--- a/core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/codeGen/CodeGeneratorImpl.kt
+++ b/core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/impl/codeGen/CodeGeneratorImpl.kt
@@ -274,6 +274,39 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
 
     private fun String.removeQuotes() = this.removeSurrounding("`")
 
+    private val troubleshootingLink = ""
+
+    /**
+     * Generate a try-catch block for column accessor with custom error messages.
+     *
+     * Catch any exception. Throws an [IllegalStateException] with a special message and original exception.
+     * Can be improved with custom exception (#1872).
+     *
+     * 1) IllegalArgumentException -> most probably column not found. Should be replaced with a custom exception (#1871)
+     * 2) ClassCastException -> most probably incorrect column type. Should be replaced with a custom exception (#1871)
+     * 3) else -> unexpected exception.
+     */
+    private fun generateTryCatchColumnAccess(columnAccessCode: String, columnName: String): String {
+        val renderedColumnName = renderStringLiteral(columnName)
+        return $$"""
+    try {
+        $$columnAccessCode
+    } catch (e: kotlin.Exception) {
+        val msg = when (e) {
+            is kotlin.IllegalArgumentException ->
+                "Column not found exception in the generated DataFrame extension property '$$renderedColumnName': ${e.localizedMessage}. See $$troubleshootingLink for more information."
+
+            is kotlin.ClassCastException ->
+                "Incorrect column type exception in generated DataFrame extension property '$$renderedColumnName': ${e.localizedMessage}. See $$troubleshootingLink for more information."
+
+            else ->
+                "Unexpected exception in generated DataFrame extension property '$$renderedColumnName'. Please report it to https://github.com/Kotlin/dataframe/issues. Exception message: $e."
+        }
+        throw IllegalStateException(msg, e)
+    }
+            """.trimIndent()
+    }
+
     private fun generatePropertyCode(
         marker: IsolatedMarker,
         shortMarkerName: String,
@@ -282,6 +315,7 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
         propertyType: String,
         getter: String,
         visibility: String,
+        columnName: String,
     ): String {
         // jvm name is required to prevent signature clash like this:
         // val DataRow<Type>.name: String
@@ -296,7 +330,7 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
         }
         return "${visibility}val$typeParameters $typeName.$name: $propertyType @JvmName(\"${
             renderStringLiteral(jvmName)
-        }\") get() = $getter as $propertyType"
+        }\") get() = ${generateTryCatchColumnAccess("$getter as $propertyType", columnName)} "
     }
 
     /**
@@ -355,6 +389,7 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
                         propertyType = columnType,
                         getter = getter,
                         visibility = visibility,
+                        columnName = it.columnName,
                     ),
                     generatePropertyCode(
                         marker = marker,
@@ -364,6 +399,7 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
                         propertyType = fieldType,
                         getter = getter,
                         visibility = visibility,
+                        columnName = it.columnName,
                     ),
                 ),
             )
@@ -378,6 +414,7 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
                             propertyType = nullableColumnType,
                             getter = getter,
                             visibility = visibility,
+                            columnName = it.columnName,
                         ),
                         generatePropertyCode(
                             marker = marker,
@@ -387,6 +424,7 @@ internal open class ExtensionsCodeGeneratorImpl(private val typeRendering: TypeR
                             propertyType = nullableFieldType,
                             getter = getter,
                             visibility = visibility,
+                            columnName = it.columnName,
                         ),
                     ),
                 )
diff --git a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/CodeGenerationTests.kt b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/CodeGenerationTests.kt
index cdf62667f6..e9a850c602 100644
--- a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/CodeGenerationTests.kt
+++ b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/CodeGenerationTests.kt
@@ -225,60 +225,125 @@ class CodeGenerationTests : BaseTest() {
     fun expectedProperties(fullTypeName: String, shortTypeName: String, addNullable: Boolean = false) =
         buildString {
             appendLine(
-                """val $dfName<$fullTypeName>.age: $dataCol<$intName> @JvmName("${shortTypeName}_age") get() = this["age"] as $dataCol<$intName>""",
+                expectedExtensionProperty(
+                    "$dfName<$fullTypeName>",
+                    "age",
+                    "$dataCol<$intName>",
+                    "${shortTypeName}_age",
+                ),
             )
             appendLine(
-                """val $dfRowName<$fullTypeName>.age: $intName @JvmName("${shortTypeName}_age") get() = this["age"] as $intName""",
+                expectedExtensionProperty("$dfRowName<$fullTypeName>", "age", intName, "${shortTypeName}_age"),
             )
             if (addNullable) {
                 appendLine(
-                    """val $dfName<$fullTypeName?>.age: $dataCol<$intName?> @JvmName("Nullable${shortTypeName}_age") get() = this["age"] as $dataCol<$intName?>""",
+                    expectedExtensionProperty(
+                        "$dfName<$fullTypeName?>",
+                        "age",
+                        "$dataCol<$intName?>",
+                        "Nullable${shortTypeName}_age",
+                    ),
                 )
                 appendLine(
-                    """val $dfRowName<$fullTypeName?>.age: $intName? @JvmName("Nullable${shortTypeName}_age") get() = this["age"] as $intName?""",
+                    expectedExtensionProperty(
+                        "$dfRowName<$fullTypeName?>",
+                        "age",
+                        "$intName?",
+                        "Nullable${shortTypeName}_age",
+                    ),
                 )
             }
             appendLine(
-                """val $dfName<$fullTypeName>.city: $dataCol<$stringName?> @JvmName("${shortTypeName}_city") get() = this["city"] as $dataCol<$stringName?>""",
+                expectedExtensionProperty(
+                    "$dfName<$fullTypeName>",
+                    "city",
+                    "$dataCol<$stringName?>",
+                    "${shortTypeName}_city",
+                ),
             )
             appendLine(
-                """val $dfRowName<$fullTypeName>.city: $stringName? @JvmName("${shortTypeName}_city") get() = this["city"] as $stringName?""",
+                expectedExtensionProperty("$dfRowName<$fullTypeName>", "city", "$stringName?", "${shortTypeName}_city"),
             )
             if (addNullable) {
                 appendLine(
-                    """val $dfName<$fullTypeName?>.city: $dataCol<$stringName?> @JvmName("Nullable${shortTypeName}_city") get() = this["city"] as $dataCol<$stringName?>""",
+                    expectedExtensionProperty(
+                        "$dfName<$fullTypeName?>",
+                        "city",
+                        "$dataCol<$stringName?>",
+                        "Nullable${shortTypeName}_city",
+                    ),
                 )
                 appendLine(
-                    """val $dfRowName<$fullTypeName?>.city: $stringName? @JvmName("Nullable${shortTypeName}_city") get() = this["city"] as $stringName?""",
+                    expectedExtensionProperty(
+                        "$dfRowName<$fullTypeName?>",
+                        "city",
+                        "$stringName?",
+                        "Nullable${shortTypeName}_city",
+                    ),
                 )
             }
             appendLine(
-                """val $dfName<$fullTypeName>.name: $dataCol<$stringName> @JvmName("${shortTypeName}_name") get() = this["name"] as $dataCol<$stringName>""",
+                expectedExtensionProperty(
+                    "$dfName<$fullTypeName>",
+                    "name",
+                    "$dataCol<$stringName>",
+                    "${shortTypeName}_name",
+                ),
             )
             appendLine(
-                """val $dfRowName<$fullTypeName>.name: $stringName @JvmName("${shortTypeName}_name") get() = this["name"] as $stringName""",
+                expectedExtensionProperty("$dfRowName<$fullTypeName>", "name", stringName, "${shortTypeName}_name"),
             )
             if (addNullable) {
                 appendLine(
-                    """val $dfName<$fullTypeName?>.name: $dataCol<$stringName?> @JvmName("Nullable${shortTypeName}_name") get() = this["name"] as $dataCol<$stringName?>""",
+                    expectedExtensionProperty(
+                        "$dfName<$fullTypeName?>",
+                        "name",
+                        "$dataCol<$stringName?>",
+                        "Nullable${shortTypeName}_name",
+                    ),
                 )
                 appendLine(
-                    """val $dfRowName<$fullTypeName?>.name: $stringName? @JvmName("Nullable${shortTypeName}_name") get() = this["name"] as $stringName?""",
+                    expectedExtensionProperty(
+                        "$dfRowName<$fullTypeName?>",
+                        "name",
+                        "$stringName?",
+                        "Nullable${shortTypeName}_name",
+                    ),
                 )
             }
             appendLine(
-                """val $dfName<$fullTypeName>.weight: $dataCol<$intName?> @JvmName("${shortTypeName}_weight") get() = this["weight"] as $dataCol<$intName?>""",
+                expectedExtensionProperty(
+                    "$dfName<$fullTypeName>",
+                    "weight",
+                    "$dataCol<$intName?>",
+                    "${shortTypeName}_weight",
+                ),
             )
             append(
-                """val $dfRowName<$fullTypeName>.weight: $intName? @JvmName("${shortTypeName}_weight") get() = this["weight"] as $intName?""",
+                expectedExtensionProperty(
+                    "$dfRowName<$fullTypeName>",
+                    "weight",
+                    "$intName?",
+                    "${shortTypeName}_weight",
+                ),
             )
             if (addNullable) {
                 appendLine("")
                 appendLine(
-                    """val $dfName<$fullTypeName?>.weight: $dataCol<$intName?> @JvmName("Nullable${shortTypeName}_weight") get() = this["weight"] as $dataCol<$intName?>""",
+                    expectedExtensionProperty(
+                        "$dfName<$fullTypeName?>",
+                        "weight",
+                        "$dataCol<$intName?>",
+                        "Nullable${shortTypeName}_weight",
+                    ),
                 )
                 append(
-                    """val $dfRowName<$fullTypeName?>.weight: $intName? @JvmName("Nullable${shortTypeName}_weight") get() = this["weight"] as $intName?""",
+                    expectedExtensionProperty(
+                        "$dfRowName<$fullTypeName?>",
+                        "weight",
+                        "$intName?",
+                        "Nullable${shortTypeName}_weight",
+                    ),
                 )
             }
         }
@@ -352,12 +417,22 @@ class CodeGenerationTests : BaseTest() {
                 val name: String
             }
 
-            val $dfName<$nestedType>.city: $dataCol<$stringName?> @JvmName("${nestedType}_city") get() = this["city"] as $dataCol<$stringName?>
-            val $dfRowName<$nestedType>.city: $stringName? @JvmName("${nestedType}_city") get() = this["city"] as $stringName?
-            val $dfName<$nestedType>.name: $dataCol<$stringName> @JvmName("${nestedType}_name") get() = this["name"] as $dataCol<$stringName>
-            val $dfRowName<$nestedType>.name: $stringName @JvmName("${nestedType}_name") get() = this["name"] as $stringName
-
-            """.trimIndent()
+            """.trimIndent() + listOf(
+                expectedExtensionProperty(
+                    "$dfName<$nestedType>",
+                    "city",
+                    "$dataCol<$stringName?>",
+                    "${nestedType}_city",
+                ),
+                expectedExtensionProperty("$dfRowName<$nestedType>", "city", "$stringName?", "${nestedType}_city"),
+                expectedExtensionProperty(
+                    "$dfName<$nestedType>",
+                    "name",
+                    "$dataCol<$stringName>",
+                    "${nestedType}_name",
+                ),
+                expectedExtensionProperty("$dfRowName<$nestedType>", "name", stringName, "${nestedType}_name"),
+            ).joinToString("\n", prefix = "\n", postfix = "\n")
 
         val declaration2 =
             """
@@ -368,13 +443,24 @@ class CodeGenerationTests : BaseTest() {
                 val weight: Int?
             }
 
-            val $dfName<$type2>.age: $dataCol<$intName> @JvmName("${type2}_age") get() = this["age"] as $dataCol<$intName>
-            val $dfRowName<$type2>.age: $intName @JvmName("${type2}_age") get() = this["age"] as $intName
-            val $dfName<$type2>.nameAndCity: $colGroup<$nestedType> @JvmName("${type2}_nameAndCity") get() = this["nameAndCity"] as $colGroup<$nestedType>
-            val $dfRowName<$type2>.nameAndCity: $dataRow<$nestedType> @JvmName("${type2}_nameAndCity") get() = this["nameAndCity"] as $dataRow<$nestedType>
-            val $dfName<$type2>.weight: $dataCol<$intName?> @JvmName("${type2}_weight") get() = this["weight"] as $dataCol<$intName?>
-            val $dfRowName<$type2>.weight: $intName? @JvmName("${type2}_weight") get() = this["weight"] as $intName?
-            """.trimIndent()
+            """.trimIndent() + listOf(
+                expectedExtensionProperty("$dfName<$type2>", "age", "$dataCol<$intName>", "${type2}_age"),
+                expectedExtensionProperty("$dfRowName<$type2>", "age", intName, "${type2}_age"),
+                expectedExtensionProperty(
+                    "$dfName<$type2>",
+                    "nameAndCity",
+                    "$colGroup<$nestedType>",
+                    "${type2}_nameAndCity",
+                ),
+                expectedExtensionProperty(
+                    "$dfRowName<$type2>",
+                    "nameAndCity",
+                    "$dataRow<$nestedType>",
+                    "${type2}_nameAndCity",
+                ),
+                expectedExtensionProperty("$dfName<$type2>", "weight", "$dataCol<$intName?>", "${type2}_weight"),
+                expectedExtensionProperty("$dfRowName<$type2>", "weight", "$intName?", "${type2}_weight"),
+            ).joinToString("\n", prefix = "\n")
 
         val expectedConverter = "it.cast<$type2>()"
 
@@ -428,11 +514,32 @@ class CodeGenerationTests : BaseTest() {
                 override val weight: kotlin.Int
             }
 
-            val $packageName.ColumnsContainer<ValidPerson>.city: $packageName.DataColumn<kotlin.String> @JvmName("ValidPerson_city") get() = this["city"] as $packageName.DataColumn<kotlin.String>
-            val $packageName.DataRow<ValidPerson>.city: kotlin.String @JvmName("ValidPerson_city") get() = this["city"] as kotlin.String
-            val $packageName.ColumnsContainer<ValidPerson>.weight: $packageName.DataColumn<kotlin.Int> @JvmName("ValidPerson_weight") get() = this["weight"] as $packageName.DataColumn<kotlin.Int>
-            val $packageName.DataRow<ValidPerson>.weight: kotlin.Int @JvmName("ValidPerson_weight") get() = this["weight"] as kotlin.Int
-            """.trimIndent()
+            """.trimIndent() + listOf(
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<ValidPerson>",
+                    "city",
+                    "$packageName.DataColumn<kotlin.String>",
+                    "ValidPerson_city",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<ValidPerson>",
+                    "city",
+                    "kotlin.String",
+                    "ValidPerson_city",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<ValidPerson>",
+                    "weight",
+                    "$packageName.DataColumn<kotlin.Int>",
+                    "ValidPerson_weight",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<ValidPerson>",
+                    "weight",
+                    "kotlin.Int",
+                    "ValidPerson_weight",
+                ),
+            ).joinToString("\n", prefix = "\n")
         assertEquals(expected, code)
     }
 
@@ -480,16 +587,65 @@ class CodeGenerationTests : BaseTest() {
                 val name: kotlin.String
                 val weight: kotlin.Int?
             }
-            
-            internal val $packageName.ColumnsContainer<DataType>.age: $packageName.DataColumn<kotlin.Int> @JvmName("DataType_age") get() = this["age"] as $packageName.DataColumn<kotlin.Int>
-            internal val $packageName.DataRow<DataType>.age: kotlin.Int @JvmName("DataType_age") get() = this["age"] as kotlin.Int
-            internal val $packageName.ColumnsContainer<DataType>.city: $packageName.DataColumn<kotlin.String?> @JvmName("DataType_city") get() = this["city"] as $packageName.DataColumn<kotlin.String?>
-            internal val $packageName.DataRow<DataType>.city: kotlin.String? @JvmName("DataType_city") get() = this["city"] as kotlin.String?
-            internal val $packageName.ColumnsContainer<DataType>.name: $packageName.DataColumn<kotlin.String> @JvmName("DataType_name") get() = this["name"] as $packageName.DataColumn<kotlin.String>
-            internal val $packageName.DataRow<DataType>.name: kotlin.String @JvmName("DataType_name") get() = this["name"] as kotlin.String
-            internal val $packageName.ColumnsContainer<DataType>.weight: $packageName.DataColumn<kotlin.Int?> @JvmName("DataType_weight") get() = this["weight"] as $packageName.DataColumn<kotlin.Int?>
-            internal val $packageName.DataRow<DataType>.weight: kotlin.Int? @JvmName("DataType_weight") get() = this["weight"] as kotlin.Int?
-            """.trimIndent()
+
+            """.trimIndent() + listOf(
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "age",
+                    "$packageName.DataColumn<kotlin.Int>",
+                    "DataType_age",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "age",
+                    "kotlin.Int",
+                    "DataType_age",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "city",
+                    "$packageName.DataColumn<kotlin.String?>",
+                    "DataType_city",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "city",
+                    "kotlin.String?",
+                    "DataType_city",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "name",
+                    "$packageName.DataColumn<kotlin.String>",
+                    "DataType_name",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "name",
+                    "kotlin.String",
+                    "DataType_name",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "weight",
+                    "$packageName.DataColumn<kotlin.Int?>",
+                    "DataType_weight",
+                    visibility = "internal ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "weight",
+                    "kotlin.Int?",
+                    "DataType_weight",
+                    visibility = "internal ",
+                ),
+            ).joinToString("\n", prefix = "\n")
         assertEquals(expected, code)
     }
 
@@ -505,7 +661,8 @@ class CodeGenerationTests : BaseTest() {
             MarkerVisibility.EXPLICIT_PUBLIC,
         ).code.declarations
         val packageName = "org.jetbrains.kotlinx.dataframe"
-        val expected = """
+        val expected =
+            """
             @DataSchema(isOpen = false)
             public interface DataType {
                 public val age: kotlin.Int
@@ -514,17 +671,66 @@ class CodeGenerationTests : BaseTest() {
                 public val weight: kotlin.Int?
             }
             
-            public val $packageName.ColumnsContainer<DataType>.age: $packageName.DataColumn<kotlin.Int> @JvmName("DataType_age") get() = this["age"] as $packageName.DataColumn<kotlin.Int>
-            public val $packageName.DataRow<DataType>.age: kotlin.Int @JvmName("DataType_age") get() = this["age"] as kotlin.Int
-            public val $packageName.ColumnsContainer<DataType>.city: $packageName.DataColumn<kotlin.String?> @JvmName("DataType_city") get() = this["city"] as $packageName.DataColumn<kotlin.String?>
-            public val $packageName.DataRow<DataType>.city: kotlin.String? @JvmName("DataType_city") get() = this["city"] as kotlin.String?
-            public val $packageName.ColumnsContainer<DataType>.name: $packageName.DataColumn<kotlin.String> @JvmName("DataType_name") get() = this["name"] as $packageName.DataColumn<kotlin.String>
-            public val $packageName.DataRow<DataType>.name: kotlin.String @JvmName("DataType_name") get() = this["name"] as kotlin.String
-            public val $packageName.ColumnsContainer<DataType>.weight: $packageName.DataColumn<kotlin.Int?> @JvmName("DataType_weight") get() = this["weight"] as $packageName.DataColumn<kotlin.Int?>
-            public val $packageName.DataRow<DataType>.weight: kotlin.Int? @JvmName("DataType_weight") get() = this["weight"] as kotlin.Int?
-            """
+            """.trimIndent() + listOf(
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "age",
+                    "$packageName.DataColumn<kotlin.Int>",
+                    "DataType_age",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "age",
+                    "kotlin.Int",
+                    "DataType_age",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "city",
+                    "$packageName.DataColumn<kotlin.String?>",
+                    "DataType_city",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "city",
+                    "kotlin.String?",
+                    "DataType_city",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "name",
+                    "$packageName.DataColumn<kotlin.String>",
+                    "DataType_name",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "name",
+                    "kotlin.String",
+                    "DataType_name",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.ColumnsContainer<DataType>",
+                    "weight",
+                    "$packageName.DataColumn<kotlin.Int?>",
+                    "DataType_weight",
+                    visibility = "public ",
+                ),
+                expectedExtensionProperty(
+                    "$packageName.DataRow<DataType>",
+                    "weight",
+                    "kotlin.Int?",
+                    "DataType_weight",
+                    visibility = "public ",
+                ),
+            ).joinToString("\n", prefix = "\n")
 
-        assertEquals(expected.trimIndent(), code)
+        assertEquals(expected, code)
     }
 
     @Test
diff --git a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ExpectedExtensionProperty.kt b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ExpectedExtensionProperty.kt
new file mode 100644
index 0000000000..1b38a44a8c
--- /dev/null
+++ b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ExpectedExtensionProperty.kt
@@ -0,0 +1,44 @@
+package org.jetbrains.kotlinx.dataframe.codeGen
+
+internal fun expectedExtensionProperty(
+    receiverType: String,
+    name: String,
+    propertyType: String,
+    jvmName: String,
+    visibility: String = "",
+    columnName: String = name.removeSurrounding("`"),
+): String =
+    buildString {
+        val renderedColumnName = columnName
+            .replace("\\", "\\\\")
+            .replace("$", "\\\$")
+            .replace("\"", "\\\"")
+            .replace("\n", "\\n")
+            .replace("\r", "\\r")
+
+        appendLine("""${visibility}val $receiverType.$name: $propertyType @JvmName("$jvmName") get() = try {""")
+        appendLine("""    this["$renderedColumnName"] as $propertyType""")
+        appendLine("} catch (e: kotlin.Exception) {")
+        appendLine("    val msg = when (e) {")
+        appendLine("        is kotlin.IllegalArgumentException ->")
+        appendLine(
+            "            \"Column not found exception in the generated DataFrame extension property " +
+                "'$renderedColumnName': \${e.localizedMessage}. See  for more information.\"",
+        )
+        appendLine("")
+        appendLine("        is kotlin.ClassCastException ->")
+        appendLine(
+            "            \"Incorrect column type exception in generated DataFrame extension property " +
+                $$"'$$renderedColumnName': ${e.localizedMessage}. See  for more information.\"",
+        )
+        appendLine("")
+        appendLine("        else ->")
+        appendLine(
+            "            \"Unexpected exception in generated DataFrame extension property " +
+                "'$renderedColumnName'. Please report it to https://github.com/Kotlin/dataframe/issues. " +
+                $$"Exception message: $e.\"",
+        )
+        appendLine("    }")
+        appendLine("    throw IllegalStateException(msg, e)")
+        append("} ")
+    }
diff --git a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/NameGenerationTests.kt b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/NameGenerationTests.kt
index 8f43fa2a23..512405a014 100644
--- a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/NameGenerationTests.kt
+++ b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/NameGenerationTests.kt
@@ -54,9 +54,12 @@ class NameGenerationTests {
     @Test
     fun `properties generation`() {
         val codeGen = ReplCodeGenerator.create()
-        val code = codeGen.process<DataRecord>().split("\n")
-        code.size shouldBe 8
-        code.forEach {
+        val propertyDeclarations = codeGen.process<DataRecord>()
+            .lineSequence()
+            .filter { it.startsWith("val ") }
+            .toList()
+        propertyDeclarations.size shouldBe 8
+        propertyDeclarations.forEach {
             it.count { it == '`' } shouldBe 2
         }
     }
diff --git a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ReplCodeGenTests.kt b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ReplCodeGenTests.kt
index 9f0bd18ad0..b172857a04 100644
--- a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ReplCodeGenTests.kt
+++ b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/ReplCodeGenTests.kt
@@ -34,6 +34,18 @@ class ReplCodeGenTests : BaseTest() {
     val intName = Int::class.simpleName!!
     val stringName = String::class.simpleName!!
 
+    private fun personProperties(marker: String) =
+        listOf(
+            expectedExtensionProperty("$dfName<$marker>", "age", "$dataCol<$intName>", "${marker}_age"),
+            expectedExtensionProperty("$dfRowName<$marker>", "age", intName, "${marker}_age"),
+            expectedExtensionProperty("$dfName<$marker>", "city", "$dataCol<$stringName?>", "${marker}_city"),
+            expectedExtensionProperty("$dfRowName<$marker>", "city", "$stringName?", "${marker}_city"),
+            expectedExtensionProperty("$dfName<$marker>", "name", "$dataCol<$stringName>", "${marker}_name"),
+            expectedExtensionProperty("$dfRowName<$marker>", "name", stringName, "${marker}_name"),
+            expectedExtensionProperty("$dfName<$marker>", "weight", "$dataCol<$intName?>", "${marker}_weight"),
+            expectedExtensionProperty("$dfRowName<$marker>", "weight", "$intName?", "${marker}_weight"),
+        ).joinToString("\n", prefix = "\n")
+
     class Test1 {
         @DataSchema
         interface _DataFrameType
@@ -95,16 +107,8 @@ class ReplCodeGenTests : BaseTest() {
                 val name: String
                 val weight: Int?
             }
-            
-            val $dfName<$marker>.age: $dataCol<$intName> @JvmName("${marker}_age") get() = this["age"] as $dataCol<$intName>
-            val $dfRowName<$marker>.age: $intName @JvmName("${marker}_age") get() = this["age"] as $intName
-            val $dfName<$marker>.city: $dataCol<$stringName?> @JvmName("${marker}_city") get() = this["city"] as $dataCol<$stringName?>
-            val $dfRowName<$marker>.city: $stringName? @JvmName("${marker}_city") get() = this["city"] as $stringName?
-            val $dfName<$marker>.name: $dataCol<$stringName> @JvmName("${marker}_name") get() = this["name"] as $dataCol<$stringName>
-            val $dfRowName<$marker>.name: $stringName @JvmName("${marker}_name") get() = this["name"] as $stringName
-            val $dfName<$marker>.weight: $dataCol<$intName?> @JvmName("${marker}_weight") get() = this["weight"] as $dataCol<$intName?>
-            val $dfRowName<$marker>.weight: $intName? @JvmName("${marker}_weight") get() = this["weight"] as $intName?
-            """.trimIndent()
+
+            """.trimIndent() + personProperties(marker)
         code shouldBe expected
 
         val code2 = repl.process<Test1._DataFrameType>()
@@ -119,10 +123,11 @@ class ReplCodeGenTests : BaseTest() {
             interface $marker3 : $markerFull {
                 override val city: String
             }
-            
-            val $dfName<$marker3>.city: $dataCol<$stringName> @JvmName("${marker3}_city") get() = this["city"] as $dataCol<$stringName>
-            val $dfRowName<$marker3>.city: $stringName @JvmName("${marker3}_city") get() = this["city"] as $stringName
-            """.trimIndent()
+
+            """.trimIndent() + listOf(
+                expectedExtensionProperty("$dfName<$marker3>", "city", "$dataCol<$stringName>", "${marker3}_city"),
+                expectedExtensionProperty("$dfRowName<$marker3>", "city", stringName, "${marker3}_city"),
+            ).joinToString("\n", prefix = "\n")
 
         code3 shouldBe expected3
 
@@ -138,10 +143,11 @@ class ReplCodeGenTests : BaseTest() {
             interface $marker5 : $markerFull {
                 override val weight: Int
             }
-            
-            val $dfName<$marker5>.weight: $dataCol<$intName> @JvmName("${marker5}_weight") get() = this["weight"] as $dataCol<$intName>
-            val $dfRowName<$marker5>.weight: $intName @JvmName("${marker5}_weight") get() = this["weight"] as $intName
-            """.trimIndent()
+
+            """.trimIndent() + listOf(
+                expectedExtensionProperty("$dfName<$marker5>", "weight", "$dataCol<$intName>", "${marker5}_weight"),
+                expectedExtensionProperty("$dfRowName<$marker5>", "weight", intName, "${marker5}_weight"),
+            ).joinToString("\n", prefix = "\n")
         code5 shouldBe expected5
 
         val code6 = repl.process<Test1._DataFrameType2>()
@@ -184,12 +190,13 @@ class ReplCodeGenTests : BaseTest() {
                 val city: String?
                 val weight: Int?
             }
-            
-            val $dfName<$marker>.city: $dataCol<$stringName?> @JvmName("${marker}_city") get() = this["city"] as $dataCol<$stringName?>
-            val $dfRowName<$marker>.city: $stringName? @JvmName("${marker}_city") get() = this["city"] as $stringName?
-            val $dfName<$marker>.weight: $dataCol<$intName?> @JvmName("${marker}_weight") get() = this["weight"] as $dataCol<$intName?>
-            val $dfRowName<$marker>.weight: $intName? @JvmName("${marker}_weight") get() = this["weight"] as $intName?
-            """.trimIndent()
+
+            """.trimIndent() + listOf(
+                expectedExtensionProperty("$dfName<$marker>", "city", "$dataCol<$stringName?>", "${marker}_city"),
+                expectedExtensionProperty("$dfRowName<$marker>", "city", "$stringName?", "${marker}_city"),
+                expectedExtensionProperty("$dfName<$marker>", "weight", "$dataCol<$intName?>", "${marker}_weight"),
+                expectedExtensionProperty("$dfRowName<$marker>", "weight", "$intName?", "${marker}_weight"),
+            ).joinToString("\n", prefix = "\n")
 
         val code = repl.process(typed).declarations.trimIndent()
         code shouldBe expected
@@ -286,22 +293,35 @@ class ReplCodeGenTests : BaseTest() {
                 val c: Int
             }
 
-            val $dfName<Leaf>.a: $dataCol<Int> @JvmName("Leaf_a") get() = this["a"] as $dataCol<Int>
-            val $dfRowName<Leaf>.a: Int @JvmName("Leaf_a") get() = this["a"] as Int
-            val $dfName<Leaf>.c: $dataCol<Int> @JvmName("Leaf_c") get() = this["c"] as $dataCol<Int>
-            val $dfRowName<Leaf>.c: Int @JvmName("Leaf_c") get() = this["c"] as Int
-
+            """.trimIndent() + listOf(
+                expectedExtensionProperty("$dfName<Leaf>", "a", "$dataCol<Int>", "Leaf_a"),
+                expectedExtensionProperty("$dfRowName<Leaf>", "a", "Int", "Leaf_a"),
+                expectedExtensionProperty("$dfName<Leaf>", "c", "$dataCol<Int>", "Leaf_c"),
+                expectedExtensionProperty("$dfRowName<Leaf>", "c", "Int", "Leaf_c"),
+            ).joinToString("\n", prefix = "\n", postfix = "\n\n") +
+            """
             @DataSchema
             interface _DataFrameType2 {
                 val col: String
                 val leaf: Leaf
             }
 
-            val $dfName<_DataFrameType2>.col: $dataCol<String> @JvmName("_DataFrameType2_col") get() = this["col"] as $dataCol<String>
-            val $dfRowName<_DataFrameType2>.col: String @JvmName("_DataFrameType2_col") get() = this["col"] as String
-            val $dfName<_DataFrameType2>.leaf: ColumnGroup<Leaf> @JvmName("_DataFrameType2_leaf") get() = this["leaf"] as ColumnGroup<Leaf>
-            val $dfRowName<_DataFrameType2>.leaf: $dfRowName<Leaf> @JvmName("_DataFrameType2_leaf") get() = this["leaf"] as $dfRowName<Leaf>
-            """.trimIndent()
+            """.trimIndent() + listOf(
+                expectedExtensionProperty("$dfName<_DataFrameType2>", "col", "$dataCol<String>", "_DataFrameType2_col"),
+                expectedExtensionProperty("$dfRowName<_DataFrameType2>", "col", "String", "_DataFrameType2_col"),
+                expectedExtensionProperty(
+                    "$dfName<_DataFrameType2>",
+                    "leaf",
+                    "ColumnGroup<Leaf>",
+                    "_DataFrameType2_leaf",
+                ),
+                expectedExtensionProperty(
+                    "$dfRowName<_DataFrameType2>",
+                    "leaf",
+                    "$dfRowName<Leaf>",
+                    "_DataFrameType2_leaf",
+                ),
+            ).joinToString("\n", prefix = "\n")
     }
 
     object TestColumnOrderInGroup {
diff --git a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/testSets/person/DataFrameTreeTests.kt b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/testSets/person/DataFrameTreeTests.kt
index 6d46279c3a..d0f7e23280 100644
--- a/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/testSets/person/DataFrameTreeTests.kt
+++ b/core/src/test/kotlin/org/jetbrains/kotlinx/dataframe/testSets/person/DataFrameTreeTests.kt
@@ -99,6 +99,7 @@ import org.jetbrains.kotlinx.dataframe.api.withNull
 import org.jetbrains.kotlinx.dataframe.api.xs
 import org.jetbrains.kotlinx.dataframe.codeGen.CodeGenerator
 import org.jetbrains.kotlinx.dataframe.codeGen.InterfaceGenerationMode
+import org.jetbrains.kotlinx.dataframe.codeGen.expectedExtensionProperty
 import org.jetbrains.kotlinx.dataframe.codeGen.generate
 import org.jetbrains.kotlinx.dataframe.columns.ColumnGroup
 import org.jetbrains.kotlinx.dataframe.columns.ColumnKind
@@ -517,21 +518,70 @@ class DataFrameTreeTests : BaseTest() {
         val nameAndCity = NameAndCity::class.qualifiedName
         val groupedColumn = ColumnGroup::class.qualifiedName
         val columnData = DataColumn::class.qualifiedName
-        val expected =
-            """
-            val $columnsContainer<$className>.age: $columnData<kotlin.Int> @JvmName("${shortName}_age") get() = this["age"] as $columnData<kotlin.Int>
-            val $dataFrameRowBase<$className>.age: kotlin.Int @JvmName("${shortName}_age") get() = this["age"] as kotlin.Int
-            val $columnsContainer<$className?>.age: $columnData<kotlin.Int?> @JvmName("Nullable${shortName}_age") get() = this["age"] as $columnData<kotlin.Int?>
-            val $dataFrameRowBase<$className?>.age: kotlin.Int? @JvmName("Nullable${shortName}_age") get() = this["age"] as kotlin.Int?
-            val $columnsContainer<$className>.nameAndCity: $groupedColumn<$nameAndCity> @JvmName("${shortName}_nameAndCity") get() = this["nameAndCity"] as $groupedColumn<$nameAndCity>
-            val $dataFrameRowBase<$className>.nameAndCity: $dataFrameRow<$nameAndCity> @JvmName("${shortName}_nameAndCity") get() = this["nameAndCity"] as $dataFrameRow<$nameAndCity>
-            val $columnsContainer<$className?>.nameAndCity: $groupedColumn<$nameAndCity?> @JvmName("Nullable${shortName}_nameAndCity") get() = this["nameAndCity"] as $groupedColumn<$nameAndCity?>
-            val $dataFrameRowBase<$className?>.nameAndCity: $dataFrameRow<$nameAndCity?> @JvmName("Nullable${shortName}_nameAndCity") get() = this["nameAndCity"] as $dataFrameRow<$nameAndCity?>
-            val $columnsContainer<$className>.weight: $columnData<kotlin.Int?> @JvmName("${shortName}_weight") get() = this["weight"] as $columnData<kotlin.Int?>
-            val $dataFrameRowBase<$className>.weight: kotlin.Int? @JvmName("${shortName}_weight") get() = this["weight"] as kotlin.Int?
-            val $columnsContainer<$className?>.weight: $columnData<kotlin.Int?> @JvmName("Nullable${shortName}_weight") get() = this["weight"] as $columnData<kotlin.Int?>
-            val $dataFrameRowBase<$className?>.weight: kotlin.Int? @JvmName("Nullable${shortName}_weight") get() = this["weight"] as kotlin.Int?
-            """.trimIndent()
+        val expected = listOf(
+            expectedExtensionProperty(
+                "$columnsContainer<$className>",
+                "age",
+                "$columnData<kotlin.Int>",
+                "${shortName}_age",
+            ),
+            expectedExtensionProperty("$dataFrameRowBase<$className>", "age", "kotlin.Int", "${shortName}_age"),
+            expectedExtensionProperty(
+                "$columnsContainer<$className?>",
+                "age",
+                "$columnData<kotlin.Int?>",
+                "Nullable${shortName}_age",
+            ),
+            expectedExtensionProperty(
+                "$dataFrameRowBase<$className?>",
+                "age",
+                "kotlin.Int?",
+                "Nullable${shortName}_age",
+            ),
+            expectedExtensionProperty(
+                "$columnsContainer<$className>",
+                "nameAndCity",
+                "$groupedColumn<$nameAndCity>",
+                "${shortName}_nameAndCity",
+            ),
+            expectedExtensionProperty(
+                "$dataFrameRowBase<$className>",
+                "nameAndCity",
+                "$dataFrameRow<$nameAndCity>",
+                "${shortName}_nameAndCity",
+            ),
+            expectedExtensionProperty(
+                "$columnsContainer<$className?>",
+                "nameAndCity",
+                "$groupedColumn<$nameAndCity?>",
+                "Nullable${shortName}_nameAndCity",
+            ),
+            expectedExtensionProperty(
+                "$dataFrameRowBase<$className?>",
+                "nameAndCity",
+                "$dataFrameRow<$nameAndCity?>",
+                "Nullable${shortName}_nameAndCity",
+            ),
+            expectedExtensionProperty(
+                "$columnsContainer<$className>",
+                "weight",
+                "$columnData<kotlin.Int?>",
+                "${shortName}_weight",
+            ),
+            expectedExtensionProperty("$dataFrameRowBase<$className>", "weight", "kotlin.Int?", "${shortName}_weight"),
+            expectedExtensionProperty(
+                "$columnsContainer<$className?>",
+                "weight",
+                "$columnData<kotlin.Int?>",
+                "Nullable${shortName}_weight",
+            ),
+            expectedExtensionProperty(
+                "$dataFrameRowBase<$className?>",
+                "weight",
+                "kotlin.Int?",
+                "Nullable${shortName}_weight",
+            ),
+        ).joinToString("\n")
         code shouldBe expected
     }
 
diff --git a/dataframe-openapi-generator/src/test/kotlin/OpenApiTests.kt b/dataframe-openapi-generator/src/test/kotlin/OpenApiTests.kt
index afdebb58e3..e3947503d7 100644
--- a/dataframe-openapi-generator/src/test/kotlin/OpenApiTests.kt
+++ b/dataframe-openapi-generator/src/test/kotlin/OpenApiTests.kt
@@ -19,6 +19,8 @@ class OpenApiTests : JupyterReplTestCase() {
 
     private val openApi = OpenApi()
     private val additionalImports = openApi.createDefaultReadMethod().additionalImports.joinToString("\n")
+    private val extensionPropertyRegex =
+        """val (.+)\.([^.:]+): (.+) @JvmName\("([^"]+)"\) get\(\) = this\["((?:\\.|[^"])*)"] as (.+)""".toRegex()
 
     private fun execGeneratedCode(code: Code): Code {
         @Language("kts")
@@ -41,6 +43,67 @@ class OpenApiTests : JupyterReplTestCase() {
         return execGeneratedCode(code)
     }
 
+    private fun String.expectedExtensionProperties(): String =
+        trimLines().lines().joinToString("\n") { line ->
+            extensionPropertyRegex.matchEntire(line)
+                ?.destructured
+                ?.let { (receiverType, name, propertyType, jvmName, columnName, castType) ->
+                    expectedExtensionProperty(
+                        receiverType = receiverType,
+                        name = name,
+                        propertyType = propertyType,
+                        jvmName = jvmName,
+                        columnName = columnName,
+                        castType = castType,
+                    )
+                }
+                ?: error("Unexpected extension property format: $line")
+        }
+
+    private fun expectedExtensionProperty(
+        receiverType: String,
+        name: String,
+        propertyType: String,
+        jvmName: String,
+        columnName: String,
+        castType: String,
+    ): String =
+        buildString {
+            val renderedColumnName = columnName
+                .replace("\\", "\\\\")
+                .replace("$", "\\\$")
+                .replace("\"", "\\\"")
+                .replace("\n", "\\n")
+                .replace("\r", "\\r")
+
+            appendLine("""val $receiverType.$name: $propertyType @JvmName("$jvmName") get() = try {""")
+            appendLine("""    this["$renderedColumnName"] as $castType""")
+            appendLine("} catch (e: kotlin.Exception) {")
+            appendLine("    val msg = when (e) {")
+            appendLine("        is kotlin.IllegalArgumentException ->")
+            appendLine(
+                "            \"Column not found exception in the generated DataFrame extension property " +
+                    "'$renderedColumnName': \${e.localizedMessage}. See  for more information.\"",
+            )
+            appendLine("")
+            appendLine("        is kotlin.ClassCastException ->")
+            appendLine(
+                "            \"Incorrect column type exception in generated DataFrame extension property " +
+                    "'$renderedColumnName': \${e.localizedMessage}. See  for more information.\"",
+            )
+
+            appendLine("")
+            appendLine("        else ->")
+            appendLine(
+                "            \"Unexpected exception in generated DataFrame extension property " +
+                    "'$renderedColumnName'. Please report it to https://github.com/Kotlin/dataframe/issues. " +
+                    "Exception message: \$e.\"",
+            )
+            appendLine("    }")
+            appendLine("    throw IllegalStateException(msg, e)")
+            append("} ")
+        }.trimLines()
+
     private val petstoreJson = File("src/test/resources/petstore.json")
     private val petstoreAdvancedJson = File("src/test/resources/petstore_advanced.json")
     private val petstoreYaml = File("src/test/resources/petstore.yaml")
@@ -111,7 +174,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Pet>.tag: kotlin.String? @JvmName("Pet_tag") get() = this["tag"] as kotlin.String?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Pet?>.tag: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullablePet_tag") get() = this["tag"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Pet?>.tag: kotlin.String? @JvmName("NullablePet_tag") get() = this["tag"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(petExtensions)
 
@@ -144,7 +207,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Error>.message: kotlin.String @JvmName("Error_message") get() = this["message"] as kotlin.String
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Error?>.message: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableError_message") get() = this["message"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Error?>.message: kotlin.String? @JvmName("NullableError_message") get() = this["message"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(errorExtensions)
 
@@ -226,7 +289,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Customer>.username: kotlin.String? @JvmName("Customer_username") get() = this["username"] as kotlin.String?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Customer?>.username: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableCustomer_username") get() = this["username"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Customer?>.username: kotlin.String? @JvmName("NullableCustomer_username") get() = this["username"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(customerExtensions)
 
@@ -256,7 +319,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Order>.status: $functionName.Status? @JvmName("Order_status") get() = this["status"] as $functionName.Status?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Order?>.status: org.jetbrains.kotlinx.dataframe.DataColumn<$functionName.Status?> @JvmName("NullableOrder_status") get() = this["status"] as org.jetbrains.kotlinx.dataframe.DataColumn<$functionName.Status?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Order?>.status: $functionName.Status? @JvmName("NullableOrder_status") get() = this["status"] as $functionName.Status?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(orderExtensions)
 
@@ -292,7 +355,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Address>.zip: kotlin.String? @JvmName("Address_zip") get() = this["zip"] as kotlin.String?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Address?>.zip: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableAddress_zip") get() = this["zip"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Address?>.zip: kotlin.String? @JvmName("NullableAddress_zip") get() = this["zip"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(addressExtensions)
 
@@ -318,7 +381,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Category>.name: kotlin.String? @JvmName("Category_name") get() = this["name"] as kotlin.String?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Category?>.name: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableCategory_name") get() = this["name"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Category?>.name: kotlin.String? @JvmName("NullableCategory_name") get() = this["name"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(categoryExtensions)
 
@@ -374,7 +437,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.User>.username: kotlin.String? @JvmName("User_username") get() = this["username"] as kotlin.String?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.User?>.username: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableUser_username") get() = this["username"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.User?>.username: kotlin.String? @JvmName("NullableUser_username") get() = this["username"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(userExtensions)
 
@@ -444,7 +507,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Pet>.tags: org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Tag?> @JvmName("Pet_tags") get() = this["tags"] as org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Tag?>
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Pet?>.tags: org.jetbrains.kotlinx.dataframe.DataColumn<org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Tag?>> @JvmName("NullablePet_tags") get() = this["tags"] as org.jetbrains.kotlinx.dataframe.DataColumn<org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Tag?>>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Pet?>.tags: org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Tag?> @JvmName("NullablePet_tags") get() = this["tags"] as org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Tag?>
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(petExtensions)
 
@@ -475,7 +538,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ApiResponse>.type: kotlin.String? @JvmName("ApiResponse_type") get() = this["type"] as kotlin.String?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.ApiResponse?>.type: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableApiResponse_type") get() = this["type"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ApiResponse?>.type: kotlin.String? @JvmName("NullableApiResponse_type") get() = this["type"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(apiResponseExtensions)
 
@@ -548,7 +611,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Dog>.tag: kotlin.String @JvmName("Dog_tag") get() = this["tag"] as kotlin.String
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Dog?>.tag: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableDog_tag") get() = this["tag"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Dog?>.tag: kotlin.String? @JvmName("NullableDog_tag") get() = this["tag"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(dogExtensions)
 
@@ -602,7 +665,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Cat>.hunts: kotlin.Boolean? @JvmName("Cat_hunts") get() = this["hunts"] as kotlin.Boolean?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Cat?>.hunts: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Boolean?> @JvmName("NullableCat_hunts") get() = this["hunts"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Boolean?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Cat?>.hunts: kotlin.Boolean? @JvmName("NullableCat_hunts") get() = this["hunts"] as kotlin.Boolean?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(catExtensions)
 
@@ -670,7 +733,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Pet>.value: kotlin.Any? @JvmName("Pet_value") get() = this["value"] as kotlin.Any?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Pet?>.value: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Any?> @JvmName("NullablePet_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Any?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Pet?>.value: kotlin.Any? @JvmName("NullablePet_value") get() = this["value"] as kotlin.Any?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(petExtensions)
 
@@ -719,7 +782,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.IntList>.list: kotlin.collections.List<kotlin.Int> @JvmName("IntList_list") get() = this["list"] as kotlin.collections.List<kotlin.Int>
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.IntList?>.list: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.collections.List<kotlin.Int>?> @JvmName("NullableIntList_list") get() = this["list"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.collections.List<kotlin.Int>?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.IntList?>.list: kotlin.collections.List<kotlin.Int>? @JvmName("NullableIntList_list") get() = this["list"] as kotlin.collections.List<kotlin.Int>?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(intListExtensions)
 
@@ -752,7 +815,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditionalProperties>.value: kotlin.String @JvmName("ObjectWithAdditionalProperties_value") get() = this["value"] as kotlin.String
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.ObjectWithAdditionalProperties?>.value: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?> @JvmName("NullableObjectWithAdditionalProperties_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.String?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditionalProperties?>.value: kotlin.String? @JvmName("NullableObjectWithAdditionalProperties_value") get() = this["value"] as kotlin.String?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(objectWithAdditionalPropertiesExtensions)
 
@@ -785,7 +848,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditional2>.value: kotlin.Any @JvmName("ObjectWithAdditional2_value") get() = this["value"] as kotlin.Any
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.ObjectWithAdditional2?>.value: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Any?> @JvmName("NullableObjectWithAdditional2_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Any?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditional2?>.value: kotlin.Any? @JvmName("NullableObjectWithAdditional2_value") get() = this["value"] as kotlin.Any?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(objectWithAdditional2Extensions)
 
@@ -818,7 +881,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditional3>.value: kotlin.Any? @JvmName("ObjectWithAdditional3_value") get() = this["value"] as kotlin.Any?
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.ObjectWithAdditional3?>.value: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Any?> @JvmName("NullableObjectWithAdditional3_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Any?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditional3?>.value: kotlin.Any? @JvmName("NullableObjectWithAdditional3_value") get() = this["value"] as kotlin.Any?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(objectWithAdditional3Extensions)
 
@@ -892,7 +955,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Error>.pets: org.jetbrains.kotlinx.dataframe.DataFrame<kotlin.Any?> @JvmName("Error_pets") get() = this["pets"] as org.jetbrains.kotlinx.dataframe.DataFrame<kotlin.Any?>
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.Error?>.pets: org.jetbrains.kotlinx.dataframe.DataColumn<org.jetbrains.kotlinx.dataframe.DataFrame<kotlin.Any?>> @JvmName("NullableError_pets") get() = this["pets"] as org.jetbrains.kotlinx.dataframe.DataColumn<org.jetbrains.kotlinx.dataframe.DataFrame<kotlin.Any?>>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Error?>.pets: org.jetbrains.kotlinx.dataframe.DataFrame<kotlin.Any?> @JvmName("NullableError_pets") get() = this["pets"] as org.jetbrains.kotlinx.dataframe.DataFrame<kotlin.Any?>
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(errorExtensions)
 
@@ -933,7 +996,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditional>.value: kotlin.Int @JvmName("ObjectWithAdditional_value") get() = this["value"] as kotlin.Int
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.ObjectWithAdditional?>.value: org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Int?> @JvmName("NullableObjectWithAdditional_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataColumn<kotlin.Int?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ObjectWithAdditional?>.value: kotlin.Int? @JvmName("NullableObjectWithAdditional_value") get() = this["value"] as kotlin.Int?
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(objectWithAdditionalExtensions)
 
@@ -980,7 +1043,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.SomeArrayContent>.value: org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Value?> @JvmName("SomeArrayContent_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Value?>
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.SomeArrayContent?>.value: org.jetbrains.kotlinx.dataframe.columns.ColumnGroup<$functionName.Value?> @JvmName("NullableSomeArrayContent_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.columns.ColumnGroup<$functionName.Value?>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.SomeArrayContent?>.value: org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Value?> @JvmName("NullableSomeArrayContent_value") get() = this["value"] as org.jetbrains.kotlinx.dataframe.DataRow<$functionName.Value?>
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(someArrayContentExtensions)
 
@@ -1019,7 +1082,7 @@ class OpenApiTests : JupyterReplTestCase() {
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ErrorHolder>.errors: org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Error> @JvmName("ErrorHolder_errors") get() = this["errors"] as org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Error>
             val org.jetbrains.kotlinx.dataframe.ColumnsContainer<$functionName.ErrorHolder?>.errors: org.jetbrains.kotlinx.dataframe.DataColumn<org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Error?>> @JvmName("NullableErrorHolder_errors") get() = this["errors"] as org.jetbrains.kotlinx.dataframe.DataColumn<org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Error?>>
             val org.jetbrains.kotlinx.dataframe.DataRow<$functionName.ErrorHolder?>.errors: org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Error?> @JvmName("NullableErrorHolder_errors") get() = this["errors"] as org.jetbrains.kotlinx.dataframe.DataFrame<$functionName.Error?>
-        """.trimLines()
+        """.expectedExtensionProperties()
 
         code should haveSubstring(errorHolderExtensions)