Merge branch '4.4'

* 4.4:
  [ErrorRenderer] FlattenException cannot be final
  Fixing issue where worker-only middleware were run in all contexts
  [Messenger] Removing "sync" transport and replacing it with much nicer config trick
  Use port 465 for SES SMTP transport
  [DI] made the `%env(base64:...)%` processor able to decode base64url
  [VarDumper] improve displaying cut closures
  Set ReturnType of LockFactory to LockInterface
  [EventDispatcher] handle lazy-callable invokable

Author: nicolas-grekas

Caster/CutStub.php

@@ -28,6 +28,11 @@ public function __construct($value)
             case 'object':
                 $this->type = self::TYPE_OBJECT;
                 $this->class = \get_class($value);
+
+                if ($value instanceof \Closure) {
+                    ReflectionCaster::castClosure($value, [], $this, true, Caster::EXCLUDE_VERBOSE);
+                }
+
                 $this->cut = -1;
                 break;