add comments custom fields after user is logged in

I believe you want is_user_logged_in

if(is_singular('debate') && is_user_logged_in()) {
  // ...
}

(Note: is_singular is misspelled in your code.)

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)