Warning strip_tags

Get this error when looking at System Diagnostics

<b>Warning</b>: strip_tags() expects parameter 1 to be string, array given in <b>/public_html/wp-content/plugins/wp-cerber/dashboard.php</b> on line <b>568</b><br />

PHP version: 7.0.6
Apache
WP: 4.5.2

https://ww.wp.xz.cn/plugins/wp-cerber/