[Bugfix] 修复关闭client失败的问题

coco/sshd.py

@@ -124,6 +124,7 @@ class SSHServer:
                 client.send_unicode(msg)
         finally:
             connection = Connection.get_connection(client.connection_id)
+            if connection:
                 connection.remove_client(client.id)
 
     def shutdown(self):