Merge pull request #831 from esistgut/patch-1

prevent "Notice: Undefined variable: attributes"

Author: soyuka

core/file-upload.md

@@ -208,7 +208,8 @@ final class ResolveMediaObjectContentUrlSubscriber implements EventSubscriberInt
             return;
         }
 
-        if (!$attributes = RequestAttributesExtractor::extractAttributes($request) || !\is_a($attributes['resource_class'], MediaObject::class, true)) {
+        $attributes = RequestAttributesExtractor::extractAttributes($request);
+        if (!$attributes || !\is_a($attributes['resource_class'], MediaObject::class, true)) {
             return;
         }