Let's pretend a tornado hits the venue and you can't deliver a cake.
Let's pretend the venue's manager goes on a bender and burns the place down.
Let's pretend that through NO FAULT of your own (an act of God, not a car accident, or you broke and arm etc) you cannot deliver the cake to a venue.
What does your contract say? What is the exact wording? I think mine might need some CYA adjustments