Showstopper issue

Every few months, I get a strange issue that fills the debug.log with gigabytes of data in a few minutes until using all available disk space, and until I restart the PHP service and delete the said log. I haven’t been able to see what’s inside such huge debug.log, until now. Gigabytes of this:

PHP Warning: Undefined variable $remval in /wp-content/plugins/pareto-security/pareto_functions.php on line 1155