Pretty much all of my non-leaf functions return Result, in application code (or where I can't be bothered to build error types as I go) I'll use anyhow to allow

Pretty much all of my non-leaf functions return Result, in application code (or where I can't be bothered to build error types as I go) I'll use anyhow to allow me to coerce pretty much anything into my result type. So unwrap can -- fairly easily -- be replaced by `?`. I'd still like to be able to agree with the compiler that it can prove that certain error cases don't happen, as with ether an unthinking propagation upwards or an unwrap I'm reliant on my own analysis to assure myself I don't need to explicitly special-case that error. If the compiler is able to dead-code eliminate the unwrap, I'd like to be able to tell the compiler that there's a bug in my code if the unwrap is still in place after optimisation.