Improve error handling for menu data fetching and update HTML structure: Enhance error logging in menuDataController, provide user-friendly error messages, and streamline the index.html file by adding new script references while removing an unused image.

src/router.js

@@ -60,10 +60,13 @@ router.beforeEach(async (to, from, next) => {
     addForgotPasswordRoute();
     addResetPasswordRoute();
     addAuthLoginRoute();
+    const fallbackMain = store.state.menuLoadError
+      ? 'ServiceUnavailableComponent'
+      : 'DefaultComponent';
     router.addRoute({
       path: '/:pathMatch(.*)*',
       components: {
-        default: loadComponent('DefaultComponent'),
+        default: loadComponent(fallbackMain),
         rightColumn: loadComponent('ImageContent')
       }
     });