How to get a text line instead of empty page out of stock procuts.

-- url of the page with the problem -- : opslagvl.nl
-- HikaShop version -- : 4.0.0
-- Joomla version -- : 3.8.13
-- PHP version -- : 7.2
-- Error-message(debug-mod must be tuned on) -- : no error

Hello,

How to get a text line instead of empty page when products from a category are out of stock. When the product is out of stock we don't want it to be shown that is allright.. The category listing displays the products of that category but when out of stock the page is empty. How can we get a text line when the category is empty.??
Hope you understand what i mean and can help us with this.

Thanks.

Mark