PHP errors

Hello and thank you for your plugin, I couldn’t do without it! Unfortunately since the recent updates, it causes errors (on all my projects). Here are the latest ones. Thank you very much!

Warning: Undefined array key “__key” in /home/XXX/public_html/XXX/wp-content/plugins/whatwedo-acf-cleaner/class/class-discovery.php on line 89

Warning: Undefined array key “__key” in /home/XXX/public_html/XXX/wp-content/plugins/whatwedo-acf-cleaner/class/class-discovery.php on line 89

Warning: Cannot modify header information – headers already sent by (output started at /home/XXX/public_html/XXX/wp-content/plugins/whatwedo-acf-cleaner/class/class-discovery.php:89) in /home/XXX/public_html/XXX/wp-admin/admin-header.php on line 9