Child theme errors

By trying to create a child theme of Gatsby by the Child Theme Configurator plugin the Analyzer of the plugin returns these errors:

Notice:  Undefined variable: charset_collate in /home/httpd/vhosts/(client)/(domain)/wp-content/plugins/companion-auto-update/companion-auto-update.php on line 54

Warning:  session_start(): Cannot send session cache limiter - headers already sent (output started at /home/httpd/vhosts/(client)/(domain)/wp-content/plugins/companion-auto-update/companion-auto-update.php:54) in /home/httpd/vhosts/(client)/(domain)/wp-content/plugins/ip2location-country-blocker/ip2location-country-blocker.php on line 824

The plugin says:
“Please contact this Theme’s author and report the items inside the box above. You may or may not be able to use this Theme as a Child Theme while these conditions exist.
It is possible that this theme has specific requirements to work correctly as a child theme. Please make sure you are using the latest version of this theme and check your theme’s documentation for more information.”

Maybe you can use this information for further development.