error: read name/message via full [[Get]] for the .stack header; drop inspect.js workaround

src/js/internal/util/inspect.js

@@ -1781,9 +1781,6 @@ function formatError(err, constructor, tag, ctx, keys) {
   const name = err.name != null ? String(err.name) : "Error";
   let stack = getStackString(err);
 
-  //! temp fix for Bun losing the error name from inherited errors + extraneous ": " with no message
-  stack = stack.replace(/^Error: /, `${name}${err.message ? ": " : ""}`);
-
   removeDuplicateErrorKeys(ctx, keys, err, stack);
 
   if ("cause" in err && (keys.length === 0 || !ArrayPrototypeIncludes(keys, "cause"))) {

test/js/node/util/node-inspect-tests/parallel/util-inspect.test.js

@@ -591,14 +591,7 @@
   // Exceptions should print the error message, not '{}'.
   {
     [new Error(), new Error("FAIL"), new TypeError("FAIL"), new SyntaxError("FAIL")].forEach(err => {
-      assert(
-        //! temp bug workaround with replace()'s
-        util.inspect(err).startsWith(err.stack.replace(/^Error: /, err.message ? "$&" : "Error")),
-        `Expected "${util.inspect(err)}" to start with "${err.stack.replace(
-          /^Error: /,
-          err.message ? "$&" : "Error",
-        )}"`,
-      );
+      assert.strictEqual(util.inspect(err), err.stack);
     });
 
     assert.throws(
@@ -3189,6 +3182,56 @@
   }
 });
 
+test("error inspect preserves stack header when name/message change after materialization", () => {
+  // Bun's native .stack already emits `${name}${message ? ": " + message : ""}` as the first line,
+  // so formatError must not rewrite it. These headers match Node's output for the same inputs.
+  const firstLine = e => util.inspect(e).split("\n")[0];
+
+  // message cleared after .stack was materialized: header is preserved verbatim
+  {
+    const err = new Error("msg");
+    void err.stack;
+    err.message = "";
+    assert.strictEqual(firstLine(err), "Error: msg");
+  }
+  {
+    const err = new Error("Error: nested");
+    void err.stack;
+    err.message = "";
+    assert.strictEqual(firstLine(err), "Error: Error: nested");
+  }
+
+  // user-assigned stack starting with "Error: " on an empty-message Error is preserved
+  {
+    const err = new Error();
+    err.stack = "Error: manually set\n    at foo";
+    assert.strictEqual(firstLine(err), "Error: manually set");
+  }
+
+  // name changed after .stack was materialized: header is not rewritten to the new name
+  {
+    const err = new Error("x");
+    void err.stack;
+    err.name = "Renamed";
+    assert.strictEqual(firstLine(err), "Error: x");
+  }
+
+  // native header is correct for subclassed errors and empty-message errors
+  {
+    class Foo extends Error {
+      name = "Foo";
+    }
+    const err = new Foo("x");
+    assert.strictEqual(err.stack.split("\n")[0], "Foo: x");
+    assert.strictEqual(firstLine(err), "Foo: x");
+  }
+  {
+    const err = new Error();
+    assert.strictEqual(err.stack.split("\n")[0], "Error");
+    assert.strictEqual(firstLine(err), "Error");
+  }
+});
+
 // Utility functions
 function runCallChecks(exitCode) {
   if (exitCode !== 0) return;