Add a new zone. Hike to back yard. Test it. Hmmm, nothing happens. Hike back to garage. Darn, forgot to put the cover onto the base AGAIN!!!
You could put a beeper in the cover that would alert when the controller was trying to open a valve but the cover is not on the base.
Better would be a pleasant message on the app when it tries to start a zone and finds the cover off.