Hi,
It's probably an issue with some old view override which doesn't work with recent versions of Joomla.
Check if you have the folder templates/YOUR_TEMPLATE/html/com_hikashop/ via FTP. If you do, rename that folder in order to deactivate all the view overrides made for HikaShop on your website and then try again after clearing any cache you might have.
It should hopefully work, confirming that the issue comes from one of the files in that folder.
I would guess it probably comes from the file templates/YOUR_TEMPLATE/html/com_hikashop/category/listing.php so the next thing would be to just rename that file (so that you don't loose all the other customized view files) and see how it goes.