Merge branch '4.4' into 5.4

* 4.4:
  MailerInterface: failed exception contract when enabling messenger
  add nonces to profiler

Author: nicolas-grekas

Mailer.php

@@ -15,8 +15,10 @@
 use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\EventDispatcher\LegacyEventDispatcherProxy;
 use Symfony\Component\Mailer\Event\MessageEvent;
+use Symfony\Component\Mailer\Exception\TransportExceptionInterface;
 use Symfony\Component\Mailer\Messenger\SendEmailMessage;
 use Symfony\Component\Mailer\Transport\TransportInterface;
+use Symfony\Component\Messenger\Exception\HandlerFailedException;
 use Symfony\Component\Messenger\MessageBusInterface;
 use Symfony\Component\Mime\RawMessage;
 use Symfony\Contracts\EventDispatcher\EventDispatcherInterface as SymfonyEventDispatcherInterface;
@@ -52,6 +54,15 @@ public function send(RawMessage $message, Envelope $envelope = null): void
             $this->dispatcher->dispatch($event);
         }
 
-        $this->bus->dispatch(new SendEmailMessage($message, $envelope));
+        try {
+            $this->bus->dispatch(new SendEmailMessage($message, $envelope));
+        } catch (HandlerFailedException $e) {
+            foreach ($e->getNestedExceptions() as $nested) {
+                if ($nested instanceof TransportExceptionInterface) {
+                    throw $nested;
+                }
+            }
+            throw $e;
+        }
     }
 }