Proper isset needed in customizer

Looks like you need to check if the variable is empty before trying to use it.

Trying to access array offset on value of type bool in /Users/dovy/Local Sites/redux4/app/public/wp-content/plugins/gutentor/includes/hooks.php on line 299

https://cloudup.com/cRctcQYHwJI

• Version 2.1.4
• PHP 7.4.1
• WordPress 5.4.2
• Gutenberg plugin NOT active.
• Using any theme (not theme related)

This only appears in the customizer.

??