$caught = function ($e, $useWindow) {
                $html = '<div class="header"> '.
                        htmlspecialchars(get_class($e)).
                        ' </div> <div class="content"> '.
                        ($e instanceof \atk4\core\Exception ? $e->getHTML() : nl2br(htmlspecialchars($e->getMessage()))).
                        ' </div>';
                $this->app->terminate(json_encode(['success' => false, 'message' => $html, 'useWindow' => $useWindow]));
            };