Wrong page when search string is empty

Hi, I implemented the filter for the product search page with checkboxes, and it all works fine except when the search string is empty. i.e.:

I start with this:

https://www.mydomain.com/?s=&post_type=product
and it shows all the products

but when I try to filter by “wine” using your plugin, it changes the url to this:
https://www.mydomain.com/?yith_wcan=1&post_type=product&product_cat=wine

removing the “s” parameter and thus getting out of the search page.

Strangely, the url of the link besides the checkbox is somewhat correct:
https://www.mydomain.com/shop/?yith_wcan=1&s&product_cat=wine

Is there any way I can prevent this page change, allowing an empty search string?

Thank you