Express Payment buttons are frozen when cancelling Apply Pay popup

[Sidsector9]

Describe the bug

This issue came out of PR #188

When there are no cards in Apple Wallet, when you click on Apple Pay it shows a popup that suggests either adding a card or cancel the flow. If cancelled, the express payment buttons are in a frozen state.

This is because when the button is clicked, it tokenizes:

const tokenResult = await button.tokenize();

but when cancelled, this line should ideally return false or throw an exception, which it doesn't.
So we don't have a way to unfreeze the buttons by detecting the flow has been cancelled.

This may be a bug in Safari or the SDK.

To reproduce

1. Remove all cards from Apple Wallet.
2. Click Apple Pay button on Shop/Cart/Checkout page.
3. Observe a popup and click Cancel.
4. Observe that the payment express buttons are frozen.

Screenshots

Expected behavior

The express payment buttons should not be frozen after clicking "Cancel" on the Apple Pay popup.