CartItems must extend AbastractCartRoute otherwise the cart is not loaded from the session

[ettoredn]

edited by @senadir

store/cart/items endpoint returns an error because cart is not loaded at that point.
This issue happens because AbstractCartRoute loads the cart before returning, CartItems didn't extend so the cart was never loaded.

Testing instructions

1- Add items to your cart.
2- From your browser console, ping store/cart/items

await (await fetch("https://EXAMPLE/wp-json/wc/store/cart/items")).json()

3- You should see a result of the current cart items.

Changelog

Fix - Make sure cart is initialized before the CartItems route is used in the Store API.

[opr]

Hi @ettoredn - thank you for this pull request! Would you be able to describe the issue you're facing along with the steps to reproduce it? This will be really helpful to give us more context about your proposed changes. Thanks in advance!

[ettoredn]

Given any non empty cart:

the endpoint /wc/store/cart/items always returns error because, as I said, the cart is not loaded from the session (via AbstractCartRoute overrides):

[senadir]

Thank you, I noticed the issue today and your PR fixes it.

I will update your PR body and merge it.