Only throw enum tables error if enum table is in exposed schema

.changeset/modern-sloths-pick.md

@@ -0,0 +1,10 @@
+---
+"graphile-build-pg": patch
+"postgraphile": patch
+---
+
+PostGraphile will only throw an error when it fails to read enum table values
+from a table in a published schema (one in the `schemas` list in your
+pgServices); enum tables in other schemas will result in a warning instead
+(since during the gather phase we don't know whether or not they will be needed
+come schema build time).

graphile-build/graphile-build-pg/src/plugins/PgEnumTablesPlugin.ts

@@ -223,15 +223,24 @@ export const PgEnumTablesPlugin: GraphileConfig.Plugin = {
              * error caused by the statement above failing.
              */
           }
-          throw new Error(`Introspection could not read from enum table "${
+          const message = `Introspection could not read from enum table "${
             pgClass.getNamespace()!.nspname
           }"."${pgClass.relname}", perhaps you need to grant access:
   GRANT USAGE ON SCHEMA "${pgClass.getNamespace()!.nspname}" TO "${role}";
   GRANT SELECT ON "${pgClass.getNamespace()!.nspname}"."${
     pgClass.relname
   }" TO "${role}";
 Original error: ${e.message}
-`);
+`;
+          // Throw error if this enum table is in an exposed schema, otherwise just warn.
+          if (
+            pgService?.schemas?.includes(pgClass.getNamespace()?.nspname ?? "")
+          ) {
+            throw new Error(message);
+          } else {
+            console.warn(message);
+            return [];
+          }
         }
       },
       async processIntrospection(info, event) {