Improve type error reporting

[mikearnaldi]

When a handler raises a non expected error we get unknown comparison, it should instead mention that the error can't be accepted. I believe this can be done by adapting the signature of the handle function

[sukovanej]

Could you please send a snippet or push this somewhere? On the type level, the error channel of a handler function is not constrained. The RouterBuilder.handle only excludes ServerError from the E and passthroughs the rest.

[mikearnaldi]

Code is all in https://github.com/mikearnaldi/lambda-conf-2024