fixup! 255e51edef

program/actions/settings/folder_reorder.php

@@ -9,7 +9,7 @@ class rcmail_action_settings_folder_reorder extends rcmail_action_settings_folde
      *
      * @param array $args Arguments from the previous step(s)
      */
-    #[Override]
+    #[\Override]
     public function run($args = [])
     {
         $rcmail = rcmail::get_instance();

program/js/app.js

@@ -8167,6 +8167,8 @@ function rcube_webmail() {
             // We need to store this information now, because it's not available anymore after removing the row from
             // the DOM.
             next_sibling = row.nextElementSibling;
+        } else {
+            next_sibling = null;
         }
 
         // get row off the list