STE needs better / safer monad fail instance

[cartazio]

I'll do that as part of making it its own package I think.

I mean, we could just not provide a monadFail instance. But that's a different discussion

[cartazio]

Also maybe we should figure out when our do notation code may be using an ill behaved monad fail in the desugaring. I don't think we have any in our code presently, but currently I don't know if we have any safeguards against that scenario