fix(payments-plugin, Mollie): Ignore completed state to prevent unneccesary error throwing

[martijnvdbrug]

Description

When a customer pays with Klarna/pay-later, and autocapture is enabled in the Mollie plugin, an error is thrown: Failed to process incoming webhook: "Unhandled incoming Mollie status 'completed' for order XXXXXXX with status 'AddingItems'"

However, this should not be an error, because autocapture makes sure the order is transitioned to PaymentSettled.

This is what happens when a customer pays with Klarna and autocapture=true in the Mollie plugin:

1. Customer pays with Klarna
2. Webhook authorized comes in from Mollie: The order is transitioned to PaymentAuthorized
3. Autocapture is triggered: The payment is settled, then the existing payment for the order is settled, transitioning the order to PaymentSettled
4. Within 200ms, we receive a webhook from Mollie with status completed, because we settled the payment in Mollie. But, I suspect the previous transaction (the transition to PaymentSettled) isn't committed yet, because the logs will say "Unhandled incoming Mollie status 'completed' for order XXXXXXX with status 'AddingItems'".

TL;DR: The completed webhook comes in before Vendure has transitioned the order to PaymentSettled, resulting in the incorrect error while the order is settled as it should.

Screenshots

Here you can see there is only ~180ms between settlement (Settled payment for XXX) and the incoming webhook (Processing status completed for xx)

Checklist

📌 Always:

• I have set a clear title
• My PR is small and contains a single feature
• I have checked my own PR

⚡ Most of the time:

• I have added or updated test cases
• I have updated the README if needed

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[martijnvdbrug]

CI test throws an Error: listen EADDRINUSE: address already in use :::3011. Local tests run just fine:

[michaelbromley]

Thanks for the detailed explanation & fix Martijn! 👍