NullReferenceException: eggs is null

NullReferenceException: object reference not set: eggs
  at Cake.addEggs(cake.c:5)
  at Cake.mix(cake.c:4)
state at failure:
  butter: creamed
  sugar: creamed
  oven: preheated
  eggs: null (carton present, empty)

Impact

Cake paused mid-mix for 25 minutes. Oven left on, heating nothing.

Root cause

An empty carton was returned to the fridge by a previous user. The check for eggs passed because the carton existed.

Resolution

A neighbor provided two eggs in exchange for a slice of the eventual cake. The creamed butter held fine at room temperature.

Action items

• Gather every ingredient before turning anything on. It finds missing items while you can still go to the store.
• Do not return empty cartons to the fridge. Checking for the container is not checking for the contents.
• Turn the oven off while you wait. It will heat up again.

# This is a blameless postmortem. The kitchen is a system. Systems fail. Cooks learn.