Fix return type handling

src/View/Helper/FormHelper.php

@@ -575,7 +575,9 @@ class FormHelper extends Helper
         $action = Router::url($url, true);
         $query = parse_url($action, PHP_URL_QUERY);
         $query = $query ? '?' . $query : '';
-        $this->_lastAction = parse_url($action, PHP_URL_PATH) . $query;
+
+        $path = parse_url($action, PHP_URL_PATH) ?: '';
+        $this->_lastAction = $path . $query;
     }
 
     /**