LibJS: Restore the environment if an exception is thrown in 'with' block

Userland/Libraries/LibJS/AST.cpp

@@ -379,12 +379,13 @@ Value WithStatement::execute(Interpreter& interpreter, GlobalObject& global_obje
 
  // 6. Let C be the result of evaluating Statement.
  auto result = interpreter.execute_statement(global_object, m_body).value_or(js_undefined());
- if (interpreter.exception())
- return {};
 
  // 7. Set the running execution context's LexicalEnvironment to oldEnv.
  interpreter.vm().running_execution_context().lexical_environment = old_environment;
 
+ if (interpreter.exception())
+ return {};
+
  // 8. Return Completion(UpdateEmpty(C, undefined)).
  return result;
 }

Userland/Libraries/LibJS/Tests/with-basic.js

@@ -15,10 +15,31 @@ test("basic with statement functionality", () => {
  }
 
  expect(object.bar).toBe(2);
+ expect(() => foo).toThrowWithMessage(ReferenceError, "'foo' is not defined");
 
  expect(bar).toBe(99);
 });
 
 test("syntax error in strict mode", () => {
  expect("'use strict'; with (foo) {}").not.toEval();
 });
+
+test("restores lexical environment even when exception is thrown", () => {
+ var object = {
+ foo: 1,
+ get bar() {
+ throw Error();
+ },
+ };
+
+ try {
+ with (object) {
+ expect(foo).toBe(1);
+ bar;
+ }
+ expect().fail();
+ } catch (e) {
+ expect(() => foo).toThrowWithMessage(ReferenceError, "'foo' is not defined");
+ }
+ expect(() => foo).toThrowWithMessage(ReferenceError, "'foo' is not defined");
+});