Symfony\Component\HttpKernel\HttpKernel::handleException PHP Method

    private function handleException(\Exception $e, $request, $type)
    {
        $event = new GetResponseForExceptionEvent($this, $request, $type, $e);
        $this->dispatcher->dispatch(KernelEvents::EXCEPTION, $event);

        // a listener might have replaced the exception
        $e = $event->getException();

        if (!$event->hasResponse()) {
            $this->finishRequest($request, $type);

            throw $e;
        }

        $response = $event->getResponse();

        // the developer asked for a specific status code
        if ($response->headers->has('X-Status-Code')) {
            $response->setStatusCode($response->headers->get('X-Status-Code'));

            $response->headers->remove('X-Status-Code');
        } elseif (!$response->isClientError() && !$response->isServerError() && !$response->isRedirect()) {
            // ensure that we actually have an error response
            if ($e instanceof HttpExceptionInterface) {
                // keep the HTTP status code and headers
                $response->setStatusCode($e->getStatusCode());
                $response->headers->add($e->getHeaders());
            } else {
                $response->setStatusCode(500);
            }
        }

        try {
            return $this->filterResponse($response, $request, $type);
        } catch (\Exception $e) {
            return $response;
        }
    }