fix(codemode): make derived error constructors inherit from Error

packages/codemode/interpreter-support.md

@@ -596,8 +596,8 @@ Nothing is exposed unless a host provides it; extension calls are not tool calls
       non-enumerable: an extension Error carries it, and this JSON form does not. Errors have no `stack`; the diagnostic
       carries a 1-based line and column in the submitted source instead.
 - [x] `instanceof` against any constructor with a `prototype`, including every built-in and `Function`.
-- [ ] The derived error constructors inheriting from `Error`: `Object.getPrototypeOf(TypeError)` is
-      `Function.prototype` here, while `TypeError.prototype` does inherit from `Error.prototype`.
+- [x] Derived error constructors extend `Error` itself: `Object.getPrototypeOf(TypeError) === Error`, so
+      `TypeError.isError` is inherited, and `TypeError.prototype` inherits from `Error.prototype`.
 - [x] Catchable user throws, runtime failures raised during interpreted evaluation, awaited tool failures, and awaited
       tool-call-limit failures; parse/compile failures, cooperative timeout, and output bounding remain outside program
       `catch`.

packages/codemode/src/interpreter/errors.ts

@@ -180,6 +180,9 @@ export const errorGlobal = <R>(type: ErrorType, ctx: Interpreter<R>) => {
       ["toString", 0, (thisValue) => errorToString(receiver(Obj, thisValue, "Error.prototype.toString"))],
     ])
     methods(builtins, ctor, [["isError", 1, (_, args) => args[0] instanceof ErrorObj]])
+    return ctor
   }
+  // Derived constructors extend Error itself, so its statics are inherited. The globals table creates Error first.
+  ctor.proto = get(builtins.Error, "constructor") as Obj
   return ctor
 }

packages/codemode/test/parity.test.ts

@@ -1461,3 +1461,19 @@ describe("structuredClone", () => {
     expect((await error(`structuredClone()`)).message).toContain("structuredClone requires 1 argument")
   })
 })
+
+describe("error constructor prototype chain", () => {
+  test("derived error constructors extend Error and inherit its statics", async () => {
+    expect(
+      await value(`
+        const derived = [TypeError, RangeError, SyntaxError, ReferenceError, EvalError, URIError, AggregateError]
+        return [
+          derived.every((ctor) => Object.getPrototypeOf(ctor) === Error),
+          Object.getPrototypeOf(Error) === Function.prototype,
+          TypeError.isError(new RangeError("x")),
+          new TypeError("x") instanceof Error,
+        ]
+      `),
+    ).toEqual([true, true, true, true])
+  })
+})

packages/codemode/test/test262/skipped.txt

@@ -207,12 +207,6 @@ language/expressions/equals/S11.9.1_A7.8.js  # #1: ({valueOf: function() {return
 language/expressions/equals/S11.9.1_A7.9.js  # #1: (true == {valueOf: function() {return 1}}) === true
 language/expressions/equals/S9.1_A1_T3.js  # #1: var object = {valueOf: function() {return 1}, toString: function() {return 0}}; object + "" ===
 built-ins/Object/freeze/throws-when-false.js  # Unknown identifier 'Proxy'.
-built-ins/Object/getPrototypeOf/15.2.3.2-2-12.js  # Object.getPrototypeOf(EvalError) Expected SameValue(«», «Error») to be true
-built-ins/Object/getPrototypeOf/15.2.3.2-2-13.js  # Object.getPrototypeOf(RangeError) Expected SameValue(«», «Error») to be true
-built-ins/Object/getPrototypeOf/15.2.3.2-2-14.js  # Object.getPrototypeOf(ReferenceError) Expected SameValue(«», «Error») to be true
-built-ins/Object/getPrototypeOf/15.2.3.2-2-15.js  # Object.getPrototypeOf(SyntaxError) Expected SameValue(«», «Error») to be true
-built-ins/Object/getPrototypeOf/15.2.3.2-2-16.js  # Object.getPrototypeOf(TypeError) Expected SameValue(«», «Error») to be true
-built-ins/Object/getPrototypeOf/15.2.3.2-2-17.js  # Object.getPrototypeOf(URIError) Expected SameValue(«», «Error») to be true
 built-ins/Object/getPrototypeOf/15.2.3.2-2-2.js  # … cannot be constructed: user-defined constructors and classes are not supported.
 built-ins/Object/isExtensible/15.2.3.13-2-24.js  # … cannot be constructed: user-defined constructors and classes are not supported.
 built-ins/Object/isExtensible/15.2.3.13-2-25.js  # … cannot be constructed: user-defined constructors and classes are not supported.