Displaying errors in apple pay sheet.

[gax97]

Is your feature request related to a problem? Please describe.
I would like to show errors if payment parameters are not valid in the apple pay sheet.

Describe the solution you'd like
Would be good to display a general error message and disallow the pay button if the shipping address isn't valid for example, or if possible show validation for particular shipping address fields, like zipcode or state.

Additional context
When "onShippingContact" event is triggered you usually need to run some logic where you calculate taxes or shipping method prices. There can be a situation where the user inputs an invalid shipping address and I don't see a way to point out that error to the user in the apple pay sheet.

[thorsten-stripe]

Thanks for flagging this. It is currently not supported and we also don't provide a way to dismiss the payment sheet, so currently can't really handle that case.

We should probably do two things

1. Allow to programmatically dismiss the payment sheet
2. Allow to provide an error in the handler for onShippingMethodSelected and onShippingContactSelected to be shown in the payment sheet.

Relevant docs

https://developer.apple.com/documentation/passkit/pkpaymentrequest
https://developer.apple.com/documentation/passkit/pkpaymenterror