Added customer_id to switch statements where it was missing
Recurring contributions were remaining "pending" in Civi and I was getting these webhook failures:
StripeIPN Exception: Event: invoice.payment_succeeded Error: Missing customer_id! StripeIPN Exception: Event: charge.succeeded Error: Missing customer_id!
It was looking for a customer id in the Invoice object and in the Charge object, which did exist but it was missing from the switch statement so it was never reached.
After adding the cases the webhooks are not failing any more and the recurring contributions are marked "in progress"