Maybe we could define a numeric identifier for each error type we have, which would let us have quite a large number of errors in an already well-known type. I

Maybe we could define a numeric identifier for each error type we have, which would let us have quite a large number of errors in an already well-known type. I guess we'd have to reserve 0 for the rare success case. In order to make sure people don't forget about it, we can even have our `main` function return an integer!