fix compatibility with the option 'hide-when-no-apps'

lib/Controller/NavController.php

@@ -27,6 +27,8 @@ use OCP\IL10N;
 use OCP\IRequest;
 use OCP\L10N\IFactory;
 use OC\URLGenerator;
+use OC;
+use OCP\IUserSession;
 
 class NavController extends Controller
 {
@@ -96,10 +98,17 @@ class NavController extends Controller
         $currentLanguage = substr($this->l10nFactory->findLanguage(), 0, 2);
         $categoriesLabels = $this->categoryFetcher->get();
         $externalSitesInTopMenu = (bool) $this->config->getAppValue('side_menu', 'external-sites-in-top-menu', 0);
+        $user = OC::$server[IUserSession::class]->getUser();
         $appsCategories = [];
         $categoriesAppsCount = [];
         $items = [];
 
+        if (!$user) {
+            return new JSONResponse([
+                'items' => $items,
+            ]);
+        }
+
         foreach ($categoriesLabels as $k => $category) {
             $categoriesLabels[$category['id']] = $category['translations'][$currentLanguage]['name'] ?? $category['translations']['en']['name'];