Gracefully handle deleted messages in MessageAttachmentObjectType

LICENSE

@@ -10,7 +10,7 @@ Additional Use Grant: You may use the Licensed Work when your application
                       uses the Licensed Work for a purpose that does neither
                       directly or indirectly generate revenue.
 
-Change Date:          2027-02-02
+Change Date:          2027-02-22
 
 Change License:       Version 2 or later of the GNU General Public License as
                       published by the Free Software Foundation.

files/lib/system/attachment/MessageAttachmentObjectType.class.php

@@ -1,12 +1,12 @@
 <?php
 
 /*
- * Copyright (c) 2010-2022 Tim Düsterhus.
+ * Copyright (c) 2010-2023 Tim Düsterhus.
  *
  * Use of this software is governed by the Business Source License
  * included in the LICENSE file.
  *
- * Change Date: 2026-09-17
+ * Change Date: 2027-02-22
  *
  * On the date above, in accordance with the Business Source
  * License, use of this software will be governed by version 2
@@ -35,6 +35,10 @@ final class MessageAttachmentObjectType extends AbstractAttachmentObjectType
         if ($objectID) {
             $message = new Message($objectID);
 
+            if (!$message->messageID) {
+                return false;
+            }
+
             \assert($message->getMessageType()->objectType === 'be.bastelstu.chat.messageType.attachment');
             $room = $message->getRoom();