Undefined variable: oldfix in metabox.php

I’m getting a php error in debug mode: `PHP Notice: Undefined variable: oldfix in /wp-content/plugins/featured-galleries/components/metabox.php on line 50′. Looks like you need to either define the $oldfix string as an empty string after line 24, or provide an isset condition on line 50.

https://ww.wp.xz.cn/plugins/featured-galleries/