From c45f7987e31dd934c2dd7adcd4f96c3d5c1f15ff Mon Sep 17 00:00:00 2001
From: wujunchen <wujunchen@baidu.com>
Date: Wed, 20 May 2026 13:23:56 +0800
Subject: [PATCH] fix: avoid stringifying locale objects

Change-Id: Ic9557acc384d5a23b3cbaaae9fea2678e9afd661
---
 src/i18n.ts               | 8 ++++----
 tests/direct-i18n.test.js | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/i18n.ts b/src/i18n.ts
index 98b4bd1..323cc4c 100644
--- a/src/i18n.ts
+++ b/src/i18n.ts
@@ -6,10 +6,10 @@ import type { PluginSettings } from './types';
 export { LOCALE_OVERRIDES, STRINGS } from './i18n-strings';
 
 function supportedBaseLanguage(value: unknown): string | null {
-  const base = String(value || '')
-    .trim()
-    .toLowerCase()
-    .split(/[-_]/)[0];
+  if (typeof value !== 'string') {
+    return null;
+  }
+  const base = value.trim().toLowerCase().split(/[-_]/)[0];
   return base && STRINGS[base] ? base : null;
 }
 
diff --git a/tests/direct-i18n.test.js b/tests/direct-i18n.test.js
index 2839c10..be87c0f 100644
--- a/tests/direct-i18n.test.js
+++ b/tests/direct-i18n.test.js
@@ -35,6 +35,7 @@ const { assert, requireBundledModule, cleanup } = require('./direct-test-setup')
     assert.strictEqual(i18n.resolveUiLanguage({ uiLanguage: 'es' }), 'es');
     assert.strictEqual(i18n.resolveUiLanguage(null), 'en');
     assert.strictEqual(i18n.resolveUiLanguage({ uiLanguage: 'auto' }), 'en');
+    assert.strictEqual(i18n.resolveUiLanguage({ uiLanguage: { toString: () => 'ja' } }), 'en');
 
     const originalNavigator = Object.getOwnPropertyDescriptor(globalThis, 'navigator');
     const setNavigatorLanguage = (language) => {