Snapshot Error with Edu-Clean Theme

Greetings, I'm getting the following error when attempting to take a snapshot:

ERROR: zip archive add failed [Array ( [type] => 8 [message] => Undefined variable: custom_height [file] => /opt/bitnami/apps/wordpress/htdocs/wp-content/themes/edu-clean/functions.php [line] => 945 ) ]

I tried excluding the edu-clean theme entirely but I still get the same error.

thanks,
ea