lib: return undefined for localStorage without file

Make localStorage return undefined and emit a warning when
--localstorage-file is not provided. Mark the property as
non-enumerable to avoid breaking {...globalThis}.

Fixes: #60303

Author: mcollina

lib/internal/util.js

@@ -688,9 +688,14 @@ function defineReplaceableLazyAttribute(target, id, keys, writable = true, check
       value: `set ${key}`,
     });
 
+    // Respect enumerability from the source module's property descriptor.
+    mod ??= require(id);
+    const descriptor = ObjectGetOwnPropertyDescriptor(mod, key);
+    const enumerable = descriptor ? descriptor.enumerable : true;
+
     ObjectDefineProperty(target, key, {
       __proto__: null,
-      enumerable: true,
+      enumerable,
       configurable: true,
       get,
       set: writable ? set : undefined,

lib/internal/webstorage.js

@@ -3,7 +3,6 @@ const {
   ObjectDefineProperties,
 } = primordials;
 const { getOptionValue } = require('internal/options');
-const { lazyDOMException } = require('internal/util');
 const { kConstructorKey, Storage } = internalBinding('webstorage');
 const { getValidatedPath } = require('internal/fs/utils');
 const kInMemoryPath = ':memory:';
@@ -12,26 +11,32 @@ module.exports = { Storage };
 
 let lazyLocalStorage;
 let lazySessionStorage;
+let localStorageWarned = false;
+
+// Check at load time if localStorage file is provided to determine enumerability.
+// If not provided, localStorage is non-enumerable to avoid breaking {...globalThis}.
+const localStorageLocation = getOptionValue('--localstorage-file');
 
 ObjectDefineProperties(module.exports, {
   __proto__: null,
   localStorage: {
     __proto__: null,
     configurable: true,
-    enumerable: true,
+    enumerable: localStorageLocation !== '',
     get() {
       if (lazyLocalStorage === undefined) {
-        // For consistency with the web specification, throw from the accessor
-        // if the local storage path is not provided.
-        const location = getOptionValue('--localstorage-file');
-        if (location === '') {
-          throw lazyDOMException(
-            'Cannot initialize local storage without a `--localstorage-file` path',
-            'SecurityError',
-          );
+        if (localStorageLocation === '') {
+          if (!localStorageWarned) {
+            localStorageWarned = true;
+            process.emitWarning(
+              'localStorage is not available because --localstorage-file was not provided.',
+              'ExperimentalWarning',
+            );
+          }
+          return undefined;
         }
 
-        lazyLocalStorage = new Storage(kConstructorKey, getValidatedPath(location));
+        lazyLocalStorage = new Storage(kConstructorKey, getValidatedPath(localStorageLocation));
       }
 
       return lazyLocalStorage;

test/parallel/test-webstorage.js

@@ -41,13 +41,22 @@ test('sessionStorage is not persisted', async () => {
   assert.strictEqual((await readdir(tmpdir.path)).length, 0);
 });
 
-test('localStorage throws without --localstorage-file', async () => {
+test('localStorage returns undefined and warns without --localstorage-file', async () => {
   const cp = await spawnPromisified(process.execPath, [
-    '-e', 'localStorage',
+    '-pe', 'localStorage',
   ]);
-  assert.strictEqual(cp.code, 1);
+  assert.strictEqual(cp.code, 0);
   assert.strictEqual(cp.signal, null);
-  assert.match(cp.stderr, /SecurityError:/);
+  assert.match(cp.stdout, /undefined/);
+  assert.match(cp.stderr, /ExperimentalWarning:.*localStorage is not available/);
+});
+
+test('localStorage is not enumerable without --localstorage-file', async () => {
+  const cp = await spawnPromisified(process.execPath, [
+    '-pe', 'Object.keys(globalThis).includes("localStorage")',
+  ]);
+  assert.strictEqual(cp.code, 0);
+  assert.match(cp.stdout, /false/);
 });
 
 test('localStorage is not persisted if it is unused', async () => {