PHP error

Hi there, we have an issue with the login functionality of the Doc Check plugin, whenever we enter Doc Check login credentials on the locked (secured) page, the WordPress error message “There has been a critical error on this website” appears. The exact error is this one: [Wed Oct 05 12:53:17.217118 2022] [php:error] [pid 26356] [client 178.21.189.13:17023] PHP Fatal error: Uncaught TypeError: property_exists(): Argument #1 ($object_or_class) must be of type object|string, null given in /var/www/html/wordpress/wp-content/plugins/doccheck-login/client/class-dcl-client.php:306\nStack trace:\n#0 /var/www/html/wordpress/wp-content/plugins/doccheck-login/client/class-dcl-client.php(306): property_exists()\n#1 /var/www/html/wordpress/wp-content/plugins/doccheck-login/client/class-dcl-client.php(230): DCL\\Client\\DCL_Client->dcl_do_login()\n#2 /var/www/html/wordpress/wp-includes/class-wp-hook.php(303): DCL\\Client\\DCL_Client->dcl_access_redirect()\n#3 /var/www/html/wordpress/wp-includes/class-wp-hook.php(327): WP_Hook->apply_filters()\n#4 /var/www/html/wordpress/wp-includes/plugin.php(470): WP_Hook->do_action()\n#5 /var/www/html/wordpress/wp-includes/template-loader.php(13): do_action()\n#6 /var/www/html/wordpress/wp-blog-header.php(19): require_once('...')\n#7 /var/www/html/wordpress/index.php(17): require('...')\n#8 {main}\n thrown in /var/www/html/wordpress/wp-content/plugins/doccheck-login/client/class-dcl-client.php on line 306, referer: https://login.doccheck.com/ We think that it is caused by the incompatibility of the Doc Check plugin with the PHP version 8.1. Is that correct? Could you please check this issue? Thank you