Do not crash if hitting a unsupported intrinsic type (#3077)

fix #3073

This still doesn't provide an optimal experience as the error shows up
on the void type instead of where it is referenced but solving that is
that long standing issue about tracing back where an error should be

.chronus/changes/fix-dont-crash-unsupported-intrinsic-2024-2-28-19-23-35.md

@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: fix
+packages:
+ - "@typespec/openapi3"
+---
+
+Do not crash if using an unsupported intrinsic type

packages/openapi3/src/schema-emitter.ts

@@ -925,7 +925,12 @@ export class OpenAPI3SchemaEmitter extends TypeEmitter<
  return { nullable: true };
  }
 
- throw new Error("Unknown intrinsic type " + name);
+ reportDiagnostic(this.emitter.getProgram(), {
+ code: "invalid-schema",
+ format: { type: name },
+ target: intrinsic,
+ });
+ return {};
  }
 
  programContext(program: Program): Context {