bug #5674 The error page can't be rendered without the context (simoh…

…einonen)

This PR was merged into the 4.x branch.

Discussion
----------

The error page can't be rendered without the context

```
Uncaught PHP Exception EasyCorp\Bundle\EasyAdminBundle\Exception\EntityNotFoundException: "The "App\Entity\Order" entity with "orderId = " does not exist in the database. The entity may have been deleted by mistake or by a "cascade={"remove"}" operation executed by Doctrine." at /app/vendor/easycorp/easyadmin-bundle/src/Factory/EntityFactory.php line 153
Uncaught Error: Symfony\Bridge\Twig\Extension\AssetExtension::getAssetUrl(): Argument #1 ($path) must be of type string, null given, called in /app/var/cache/prod/twig/ff/ffe222c63463562719428a9eb08ba9a2.php on line 206
Uncaught PHP Exception TypeError: "Symfony\Bridge\Twig\Extension\AssetExtension::getAssetUrl(): Argument #1 ($path) must be of type string, null given, called in /app/var/cache/prod/twig/ff/ffe222c63463562719428a9eb08ba9a2.php on line 206" at /app/vendor/symfony/twig-bridge/Extension/AssetExtension.php line 46
```

In production `EntityNotFoundException` turns from 404 into 500 because the rendering failed here. Pretty annoying because 404s can just be ignored but 500 is something that should probably be looked at.

There's also #5477 which fixes this but this is should be a lot simpler

Commits
-------

eef7c68 The error page can't be rendered without the context

src/EventListener/ExceptionListener.php

@@ -46,6 +46,10 @@ public function onKernelException(ExceptionEvent $event)
             return;
         }
 
+        if (null === $this->adminContextProvider->getContext()) {
+            return;
+        }
+
         // TODO: check why these custom error pages don't work
         $event->setResponse($this->createExceptionResponse(FlattenException::create($exception)));
     }