Have you ever seen a code comment saying “this should never happen”? Have you ever wondered what would happen if it did? Swift has a diverse set of error-handling capabilities, from using throw to send errors up the stack to using a Result to handle errors in asynchronous methods. In this talk, we’ll look at the landscape of handling errors in Swift, create new ways of expressing and handling them, and show how even the most impossible code-level situations can have 100% test coverage. By the end, you’ll be taking control of the errors in your code, instead of letting them take control of you.