[PoC] [RFC] Allow routes to return anyhow::Error

[thomaseizinger]

Using anyhow allows for really ergonomic error handling in Rust code. Unfortunately, these ergonomics end at the integration layer with warp. Currently, we work around this by having separate handler functions that return an anyhow::Result which we then pack into a rejection (we also have an intermediary step for HttpApiProblem but that is not important at this stage):

https://github.com/comit-network/comit-rs/blob/301eb63afea6327df8eb7281bc8251090cc120a3/cnd/src/http_api/routes.rs#L30-L37

I am putting this PR up as a proof-of-concept to show that we could improve ergonomics here fairly easily :)

I wasn't quite sure how to deal with the CombineRejection trait. The compiler complained so I implemented it in a way that seems to work but I feel that this was not the original purpose of it.

[jxs]

Hi, this has already been discussed, see #527, #374

[thomaseizinger]

Hi, this has already been discussed, see #527, #374

I am aware of these discussions, I was even part of some of them :)
The reason I am opening this PR is because in my opinion this was never properly addressed.
Ironically, #307 was just brought to my attention again through a different comment so I am gonna try and continue the discussion there!