[PLUGINS][Reply] Array key 'reply_to' checked if it exists.

Plugin\Reply\Entity\NoteReply::getReplyToNote lacked a check to make sure the 'reply_to' key existed within the array resulting from the query.

plugins/Reply/Entity/NoteReply.php

@@ -95,7 +95,7 @@ class NoteReply extends Entity
         $result = DB::dql('select nr.reply_to from note_reply nr '
             . 'where nr.note_id = :note_id', ['note_id' => $note->getId()], );
 
-        if (!empty($result)) {
+        if (!\is_null($result) && \array_key_exists('reply_to', $result)) {
             return $result['reply_to'];
         }