Merge pull request #6 from HanSon/dev

修复撤回历史消息报错

src/Message/Entity/Recall.php

@@ -49,12 +49,15 @@ class Recall extends Message implements MessageInterface
         $msgId = $this->parseMsgId($this->msg['Content']);
 
         /** @var Message $message */
-        $this->origin = $message = message()->get($msgId);
-        $this->nickname = $message->sender ? $message->sender['NickName'] : account()->getAccount($message->msg['FromUserName'])['NickName'];
+        $this->origin = $message = message()->get($msgId, null);
 
+        if(!$message){
+            $this->nickname = $message->sender ? $message->sender['NickName'] : account()->getAccount($message->msg['FromUserName'])['NickName'];
             $this->setContent();
         }
 
+    }
+
     private function setContent()
     {
         $this->content = "{$this->nickname} 刚撤回了消息";