Array error appearing on pages

I wanted to mention this incase it’s happening to more people than me.

I am receiving a warning at the bottom of my page under the footer that reads:

Warning: array_intersect(): Argument #1 is not an array in /homepages/20/d343185278/htdocs/wp-includes/class-wp-customize-widgets.php on line 1176

Warning: array_values() expects parameter 1 to be array, null given in /homepages/20/d343185278/htdocs/wp-includes/class-wp-customize-widgets.php on line 1176

I can guess what this alludes to, but no idea how to fix it.

here is an image of what it looks like on the page:
https://tinypic.com/r/29mr9ty/8

thanks for any feedback!