Ojs\CoreBundle\Listeners\ExceptionListener::onHasRelationException PHP Метод

    private function onHasRelationException(GetResponseForExceptionEvent $event)
    {
        $request = $this->requestStack->getMasterRequest();
        /** @var HasRelationException $exception */
        $exception = $event->getException();
        $errorText = $exception->getErrorMessage();
        if ($request->get('_format') == 'json') {
            $response = new JsonResponse(['error' => $errorText]);
            $event->setResponse($response);
            return;
        }
        $routeArr = $this->getRefererParams($event->getRequest());
        $route = $routeArr['_route'];
        unset($routeArr['_route']);
        unset($routeArr['__controller']);
        $this->session->getFlashBag()->add('danger', $errorText);
        $url = $this->router->generate($route, $routeArr);
        $response = new RedirectResponse($url);
        $event->setResponse($response);
    }