Fix error when discarding changes to the display order

[malithsen]

Fixes #3697

Changes proposed in this Pull Request:

When changes to the payment method order list are discarded via the cancel button, it leads to an empty settings screen. This happens because it tries to find a non-existent Link payment method in the mapping list. This PR fixes it by returning early if the Icon and label fields for a payment method are not found on the mapping.

Before

Now

Testing instructions

Test the fix

1. Go to WooCommerce -> Settings -> Payments -> Stripe
2. Click on "Change display order" button at the top right.
3. Click the cancel button.
4. Settings page should not be an empty screen.

Regression tests

• Make sure changes to the payment method list are retained and reflected on the checkout page.

---

• Covered with tests (or have a good reason not to test in description ☝️)
• Added changelog entry in both changelog.txt and readme.txt (or does not apply)
• Tested on mobile (or does not apply)

Post merge

• Added testing instructions to the Release Testing Instructions wiki page (or does not apply)
• Added the needs docs label (or does not apply)
• Included this PR in the Release Thread scope (or does not apply)

[Mayisha]

Thank you @malithsen for the fix. With these additional checks, I don't see the empty screen issue anymore. 👍

But there is another issue. It shows a wrong list after I click the cancel button.

Screen.Recording.2025-01-10.at.11.58.38.AM.mov

We should fix it here as well to render the correct order.

The empty screen error is happening because upePaymentMethods in the above line includes link in the list. Also, the upePaymentMethods list is different than the orderedPaymentMethodIds list in terms of ordering.
Using setOrderedPaymentMethodIds( orderedPaymentMethodIds ); here won't help as we are updating orderedPaymentMethodIds when user drags a method to reorder.

We have to either store the initial data of orderedPaymentMethodIds in this component to use them when cancel button is clicked or keep the list in different state variable in this component. You may have some other better solutions too.