PHP Critical Error after search

PHP Fatal error: Uncaught ValueError: strpos(): Argument #3 ($offset) must be contained in argument #1 ($haystack) in /chroot/home/a4e85b26/e2fd050c09.nxcli.net/html/wp-content/plugins/wp-slimstat/admin/index.php:220

I receive this error after performing searches within the site. I narrowed it down to the length of the temp string being different after it is sanitized and unslashed. This error only happens when logged into wp-admin and relates to the temp variable being the wrong length.