[Defender Pro] Defender - Masked Login Area generates a 500 screen, instead of a a 404

the expected behaviour is that when someone visits the wp-login.php to be presented with a 404 page, but instead there is a 500 generated page with the "This feature is disabled" message on.

The plugin even allows you to redirect the 404 hits to a page, but that will not work since, as said, no 404 gets generated.