Fatal Error in Widgets area on php8 (fix provided)

There is a fatal error when using php 8 in the widgets section causing the sidebar areas to disappear.

The error is caused by $excluded_categories not being an array when it’s passed as the second argument to the in_array() function.

First, you should make sure that $instance['excluded_categories'] is always an array. If not, you can default it to an empty array. This can be done replacing line 354 with the following:

$excluded_categories = isset($instance[‘excluded_categories’]) && is_array($instance[‘excluded_categories’]) ? $instance[‘excluded_categories’] : [];