On checkout, canProceedToPayment never actually checks shippingAddress' streetLine1 or postalCode

[floze]

This expression never yields false:

storefront-remix-starter/app/routes/checkout/index.tsx

Line 74 in e32cebd

selectedAddressIndex != null) &&

...since the initialized value is 0, not null:

storefront-remix-starter/app/routes/checkout/index.tsx

Line 61 in e32cebd

const [selectedAddressIndex, setSelectedAddressIndex] = useState(0);

Setting null as the initial value messes up the address selectors default selection, so this needs to be taken care of as well.

It would be wise, I suppose, to furthermore switch all the validations to Remix ValidatedForm / Zod...

[kyunal]

First of all, thanks for pointing this out. Just like with the other issue, I will see if I can tackle this some time soon, but contributions are very welcome.

It would be wise, I suppose, to furthermore switch all the validations to Remix ValidatedForm / Zod...

I totally agree with this, and this would be my favourite solution. The current implementation is less than ideal and not in-line with how validations are done in the rest of the project.