Steps to reproduce:

1. Log in to storefront.
2. Go to /product-catalog or product page.
3. Click 'Add to cart' button while page is still loading.
4. Verify web browser console output.

Actual result:

See attached screenshots

Sometimes adding product to cart cause a JS exception and product is not added to cart.

Uncaught TypeError: Cannot read properties of null (reading 'entries')
    at StorefrontCart.getProductEntry (ibexa-storefront-cart-js.js:230:40)
    at StorefrontCart.addProduct (ibexa-storefront-cart-js.js:244:31)
    at StorefrontAddToCart.handleAddToCart (ibexa-storefront-cart-js.js:63:26)
    at StorefrontAddToCart.handleAddToCart (ibexa-storefront-cart-js.js:997:85)

Expected result:

Even when page is loaded an request is sent and product is added to the cart.

Note:
Problem exists for standard and variant products