Traceback (most recent call last):
  File "/srv/app/api/views.py", line 96, in create_order
    total = compute_total(cart, customer.discount_rate)
  File "/srv/app/api/pricing.py", line 38, in compute_total
    return subtotal * (1 - rate)
                       ~~~~~~~~^~~~~~
TypeError: unsupported operand type(s) for -: 'int' and 'NoneType'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/srv/app/api/views.py", line 101, in create_order
    log.error("pricing failed for %s", customer.id)
AttributeError: 'NoneType' object has no attribute 'id'