错误提示

每次点开WPJAM插件的讨论组选项卡，就出现这个提示，麻烦懂代码的大牛看一下，什么问题，谢谢！(网站环境：centos7.3 mysql5.5 php7.3）

Notice: Undefined index: user in /home/wwwroot/lnmp7311/domain/jingzane.com/web/wp-content/plugins/wpjam-basic/admin/pages/wpjam-topics.php on line 221 Notice: Undefined index: user in /home/wwwroot/lnmp7311/domain/jingzane.com/web/wp-content/plugins/wpjam-basic/admin/pages/wpjam-topics.php on line 222 Notice: Undefined index: user in /home/wwwroot/lnmp7311/domain/jingzane.com/web/wp-content/plugins/wpjam-basic/admin/pages/wpjam-topics.php on line 224 Notice: Undefined index: user in /home/wwwroot/lnmp7311/domain/jingzane.com/web/wp-content/plugins/wpjam-basic/admin/pages/wpjam-topics.php on line 256