fix nullsafe warnings

_define.php

@@ -10,7 +10,7 @@
  * @copyright Jean-Christian Denis
  * @copyright GPL-2.0 https://www.gnu.org/licenses/gpl-2.0.html
  */
-if (!defined('DC_RC_PATH')) {
+if (!defined('DC_RC_PATH') || is_null(dcCore::app()->auth)) {
     return;
 }
 
@@ -22,7 +22,7 @@ $this->registerModule(
     [
         'requires'    => [['core', '2.26']],
         'permissions' => dcCore::app()->auth->makePermissions([
-            dcAuth::PERMISSION_ADMIN,
+            dcCore::app()->auth::PERMISSION_ADMIN,
         ]),
         'type'       => 'plugin',
         'support'    => 'https://github.com/JcDenis/' . basename(__DIR__),

src/Backend.php

@@ -43,6 +43,11 @@ class Backend extends dcNsProcess
 
         dcCore::app()->addBehaviors([
             'adminBlogPreferencesFormV2' => function (dcSettings $blog_settings): void {
+                // nullsafe
+                if (is_null(dcCore::app()->blog)) {
+                    return;
+                }
+
                 $exists = [];
                 $path   = Path::fullFromRoot((string) $blog_settings->get('system')->get('public_path'), DC_ROOT);
                 foreach (['ico', 'png', 'bmp', 'gif', 'jpg', 'mng'] as $ext) {

src/Frontend.php

@@ -34,7 +34,7 @@ class Frontend extends dcNsProcess
         }
 
         dcCore::app()->addBehavior('publicHeadContent', function (): void {
-            if (!dcCore::app()->blog->settings->get('system')->get('simply_favicon')) {
+            if (is_null(dcCore::app()->blog) || !dcCore::app()->blog->settings->get('system')->get('simply_favicon')) {
                 return;
             }
 

src/UrlHandler.php

@@ -31,6 +31,11 @@ class UrlHandler extends dcUrlHandlers
 
     public static function simplyFaviconUrl(string $arg): void
     {
+        // nullsafe
+        if (is_null(dcCore::app()->blog)) {
+            return;
+        }
+
         $public_path = Path::fullFromRoot(dcCore::app()->blog->settings->get('system')->get('public_path'), DC_ROOT);
 
         if (dcCore::app()->blog->settings->get('system')->get('simply_favicon')