PHP fatal errors

Hello,
we’re seeing a lot of PHP fatal errors in our server error logs:

PHP Fatal error: Uncaught TypeError: Argument 1 passed to FernleafSystems\\Wordpress\\Plugin\\Shield\\Modules\\Data\\DB\\IPs\\IPRecords::loadIP() must be of the type string, null given, called in /nas/content/live/site/wp-content/plugins/wp-simple-firewall/src/lib/src/Modules/Data/DB/UserMeta/MetaRecords.php on line 46 and defined in /nas/content/live/site/wp-content/plugins/wp-simple-firewall/src/lib/src/Modules/Data/DB/IPs/IPRecords.php:14\nStack trace:\n#0 /nas/content/live/site/wp-content/plugins/wp-simple-firewall/src/lib/src/Modules/Data/DB/UserMeta/MetaRecords.php(46): FernleafSystems\\Wordpress\\Plugin\\Shield\\Modules\\Data\\DB\\IPs\\IPRecords->loadIP(NULL, true)\n#1 /nas/content/live/site/wp-content/plugins/wp-simple-firewall/src/lib/src/Modules/Data/DB/UserMeta/MetaRecords.php(24): FernleafSystems\\Wordpress\\Plugin\\Shield\\Modules\\Data\\DB\\UserMeta\\MetaRecords->addMeta(213635)\n#2 /nas/content/live/site/wp-content/plugins/wp-simple-firewall/src/lib/src/Users/UserMetas.php(61): FernleafSystems\\Wordpress\\Plugin\\Shield\\Modules\\Data\\DB\\ in /nas/content/live/site/wp-content/plugins/wp-simple-firewall/src/lib/src/Modules/Data/DB/IPs/IPRecords.php on line 14, referer: https://site.com/wp-login.php?redirect_to=https%3A%2F%2Fsite.com