Used mode to determine flow for checkout session (#184)
Used mode to determine flow for checkout session (#184)

no-issue

This fixes a problem when subscribing to a Plan (Price) with a default
trial period. We also add logging to add a little more information about
which flow we're entering.

Subscriptions that are started with a trial have a `setup_intent`
present on the Checkout Session object, which was incorrectly causing us
to determine that we are in a "setup" flow and attempt to update a
customers card details.

We now use the `mode` property of the Checkout Session to determine
whether we are handling a new Subscription, or if we are in a "setup"
flow and should update the Customer's card details.
TryGhost/Ghost,TryGhost/Ghost,TryGhost/Ghost