I am relatively new to wordpress development, I am trying to extend 'Walker_Category_Checklist' class found in
/wp-admin/includes/class-walker-category-checklist.php to customize it for
wp_category_checklist() but when I try to
require_once a link to my extended class in the child-theme
function.php I get this error and site not loading!
x" Fatal error: Class 'Walker_Category_Checklist' not found in ..... "
Is it because of this class file in 'wp-admin/includes/' dir? if so then how to extend it ?
wordpress ver: 5.6 - php ver: 7.2
Thanks in advance Cheers Mo.