plugin mess with WP theme editor?

I installed this plugin and it works great!

However, later I noticed that when I tried to go to Appearance > Editor to edit something in functions.php, I was unable to. I received an error called “Unable to communicate back with site to check for fatal errors, so the PHP change was reverted. You will need to upload your PHP file change by some other means, such as by using SFTP”.

I checked every plugin I have and found out that your plugin was at fault. Is there any way I can resolve this?