fix: handle unsupported language prefixes and avoid blank screen

src/router/index.ts

@@ -43,16 +43,29 @@ router.beforeEach(async (to) => {
   
   // 1. Handle Language Prefix
   let lang = to.params.lang as string;
+  const savedLang = localStorage.getItem('locale') || 'en';
   
   if (!lang) {
-    const savedLang = localStorage.getItem('locale') || 'en';
-    // Redirect /orders to /en/orders
+    // If no lang prefix (e.g. /auth), redirect to /en/auth or /savedLang/auth
+    // Check if the path already starts with a lang-like prefix that isn't supported
+    const firstSegment = to.path.split('/')[1];
+    if (firstSegment && !supportedLangs.includes(firstSegment) && firstSegment.length === 2) {
+      // It looks like an invalid lang code (e.g. /fr/auth), replace it
+      const newPath = to.fullPath.replace(`/${firstSegment}`, `/${savedLang}`);
+      return { path: newPath };
+    }
     return { path: `/${savedLang}${to.fullPath}` };
   }
 
   // 2. Sync i18n
-  if (supportedLangs.includes(lang) && i18n.global.locale.value !== lang) {
-    await setLanguage(lang);
+  if (supportedLangs.includes(lang)) {
+    if (i18n.global.locale.value !== lang) {
+      await setLanguage(lang);
+    }
+  } else {
+    // Unsupported lang in params? Redirect to savedLang
+    const newPath = to.fullPath.replace(`/${lang}`, `/${savedLang}`);
+    return { path: newPath };
   }
 
   // 3. Auth Guards