Fix fatal error when payment method ID is missing

[wjrosa]

Fixes #3934

Changes proposed in this Pull Request:

This PR fixes a possible fatal error that might happen when a payment method ID could not be retrieved, by setting some default values during payment information array initialization.

Testing instructions

Code review should be enough.

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• Covered with tests (or have a good reason not to test in description ☝️)
• Tested on mobile (or does not apply)

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[Mayisha]

Adding these default values is a good idea and will prevent the fatal error. 👍

[annemirasol]

@wjrosa Can we exclude the default capture method at this level? Amazon Pay doesn't like it and complains (when capture method is manual), because it needs to be under payment_method_options?