fix: return 503 JSON from FallbackExceptionListener for health/info routes

The fallback exception listener redirected all unhandled exceptions to
the feedback page, which would return a 301 instead of an error status
for the health and info endpoints. Return a JSON 503 response instead
for these paths, consistent with the monitor-bundle DOWN format.

Author: kayjoosten

src/OpenConext/EngineBlockBundle/EventListener/FallbackExceptionListener.php

@@ -21,6 +21,7 @@
 use EngineBlock_Exception;
 use OpenConext\EngineBlockBridge\ErrorReporter;
 use Psr\Log\LoggerInterface;
+use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpKernel\Event\ExceptionEvent;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
@@ -76,6 +77,15 @@ public function onKernelException(ExceptionEvent $event)
             $exception->getMessage()
         ));
 
+        $path = $event->getRequest()->getPathInfo();
+        if (in_array($path, ['/health', '/internal/health', '/info', '/internal/info'], true)) {
+            $event->setResponse(new JsonResponse(
+                ['status' => 'DOWN', 'message' => $exception->getMessage()],
+                JsonResponse::HTTP_SERVICE_UNAVAILABLE
+            ));
+            return;
+        }
+
         if ($exception instanceof EngineBlock_Exception) {
             $this->errorReporter->reportError($exception, 'Caught Unhandled EngineBlock_Exception');
         } else {