Cannot finish checkout process when a user applies a giftcard

[QAComet]

Description

If you go through the checkout process and use a giftcard which makes the total zero, then the payment step in checkout gets stuck in an infinite loading loop, and just shows the loader animation. See the screenshot below

Steps to reproduce

• In the medusa admin page create a giftcard with a balance of 100
• Go to the store page
• Add a product which costs less than $50 into the cart
• Navigate to the cart page
• Add in the valid giftcard
• Go to checkout
• Fill in the shipping address form and go to the shipping step
• Select the shipping service and go to the payment step
• You should see this infinite loader

Suggestions for improvement

• One option is to remove the payment step if a giftcard has been applied
• Another is to not load a payment option, and just display the finish checkout button

[QAComet]

Note: if I go ahead and click the trash icon for the giftcard, found on the far right side of the page, then the payment form will immediately appear.

[VariableVic]

Just merged a fix, could you have a look and confirm if this solves the issue for you? @QAComet