A product in Drupal Commerce 2 has limited stock. Users can add-to-cart so long as there is a current stock value > 0, and stock is decremented at the order-placed stage. If a second concurrent user passes the order-placed stage first and has used all available stock, when user 2 gets to the order-placed stage I want to take action (remove item from cart, show a message, do something if no other items in cart..).
I am catching 'commerce_order.place.pre_transition' event, and can manipulate order items, but I'm not sure if I'll mess up other DC processes. Would it be better to have a CheckoutPane plugin to do something pre-placement at/after the Review stage, or something else? The action needs to be taken just pre payment attempt.