Hello,
This error indicates that a field in the Theme Settings that should have a number, does not have any or contains letters, for example. I have checked the Theme Settings and see you specified nothing in the Theme Settings > Product Archives > Product Grid: Товаров на странице. I have set “20” and I do not see any errors on the Wishlist: https://gyazo.com/7f099a9c0ef3dd3df2281cb3a1da1e3a
You can change this value for that one you need, however, it cannot be empty.
Best Regards