Worpress popup issue

Dear Sir / Madam,

I need some help with our website.
We have an warning, it does not effect the work of the website but it does show this warning to all customers.

After updated a few add-ons and the latest WordPress version I am getting a message on our homepage.

Warning: Invalid argument supplied for foreach() in /home/******/domains/cocoint.biz/public_html/vierdaagse/wp-content/plugins/wordpress-popup/inc/class-popup-base.php on line 638

https://vierdaagse.cocoint.biz/

If I check from line 638:

foreach ( $popup_ids as $id ) {
			$popup = IncPopupDatabase::get( $id );			

			if ( $popup_id ) {
				// Forced popup ignores all conditions.
				$show = true;
			} else {
				// Apply the conditions to decide if the popup should be displayed.
				$show = apply_filters( 'popup-apply-rules', true, $popup );
			}