Hi,
If you search for __PS_BASE_URI__ on Google, you'll find that this is a constant from PrestaShop. This constant does not exist in HikaShop.
Also, the product / cart.php view file of HikaShop is located in a folder like this: components/com_hikashop/views/product/tmpl/cart.php
And its override is located in templates/YOUR_TEMPLATE/html/com_hikashop/product/cart.php
Note that in the override file path, there is no "tmpl" between the product and cart parts of the path, like in your message. So it's likely that this comes from a view override of product / cart.php
Maybe some code copy / pasted from a PrestaShop which the website was using before switching to HikaShop or something like that ?