[breaking] Remove `anyhow` from default features

[LeoniePhiline]

[breaking] Remove `anyhow` from default features

[LeoniePhiline]

Update: This change is planned to go into the next breaking release, since introducing a (default) anyhow feature flag ended up being an unintended breaking change.

@ten3roberts responded to my question "Since it's a breaking change anyway, shall we then remove it from default features right away?" with:

Absolutely, that would be great.

It would further go into our intents of making the error wrapping represent a logical error chain, rather than context attached to an error. The anyhow compatibility has unfortunately incentivized the latter approach where through API naming the error chains are treated like context stores where you can interpolate arbitrary data, such as usernames or other variables.

Making it opt-in would thus be awesome, and push towards a more descriptive chain of errors.

Do you mind opening a PR with a short explanation in the Readme of what it means and how to opt in/how it compares to anyhow?

[LeoniePhiline]

Status: Waiting for #149 due to some thematic overlap.