Undefined constant (with solution).

There are 4 errors in the code. Those result in the WP Dashboard showing the user as “disabled”, but that is technically not soand the user can still log in. ??
The created custom database table also remains empty, btw.

The update & check when a users tries to log in have the same “undefined constant” error -> “dwul_disable_user_email”. So nothing can be saved to the database and nothing can be checked.

The solution is simple: ??
In custom-ajax.php:
Change lines 38, 91 & 139 to:
$table_name = $wpdb->prefix . 'dwul_disable_user_email';

And line 39 to:
$exitingusertbl = $wpdb->prefix .'users';