Hello,
Please check if comments are enabled in your course edit page in back end .
refer : https://prnt.sc/g3uqov
when you add this code in your wplms-customizer.php file in wplms customizer plugin :
function bp_remove_nav_tabs() {
global $bp;
bp_core_remove_nav_item( 'course' );
}
add_action( 'bp_setup_nav', 'bp_remove_nav_tabs', 15 );
It will hide the course nav.
Please share your page url where you are getting this error and also share admin-credentials in a private reply so that i can check this issue.