error notice

Hi

have been using your plugin for a long time but since a few weeks I get an error message on the wp-login page-
Trying to access array offset of type bool in wp-content/plugins/birds-custom-login/admin/settings/apply-css.php

I can see you have not replied to last messages really like the simplicity of this plugin, hppe you continue working on it!

The page I need help with: [log in to see the link]