Search Doesn't Return Results – mysql_real_escape_string Error

Hello,

I found an issue with the plugin not functioning due to the mysql_real_escape_string, I found nothing was being returned except the following errors;

WARNING: wp-content/plugins/improved-user-search-in-backend/improved-user-search-in-backend.php:50 - mysql_real_escape_string(): Access denied for user '***'@'localhost' (using password: NO)
WP_Users_List_Table->prepare_items, WP_User_Query->__construct, WP_User_Query->prepare_query, do_action_ref_array, call_user_func_array, user_search_by_multiple_parameters, mysql_real_escape_string
WARNING: wp-content/plugins/improved-user-search-in-backend/improved-user-search-in-backend.php:50 - mysql_real_escape_string(): A link to the server could not be established
WP_Users_List_Table->prepare_items, WP_User_Query->__construct, WP_User_Query->prepare_query, do_action_ref_array, call_user_func_array, user_search_by_multiple_parameters, mysql_real_escape_string

Looking into the error it appears the function is deprecated for PHP 5.5, I tried the msqli version ( mysqli_real_escape_string but that requires a db connection. I found that establishing one can be avoided by simply using the wpdb escape function $wpdb->escape(). So the fix is to update line 50 as follows;
$qstr = $wpdb->escape($_GET["s"]);

Hope this helps someone.
Cheers

https://wordpress.org/plugins/improved-user-search-in-backend/