feat: impl StackError for anyhow:::Error

[Frando]

Description

Adds impl StackError for anyhow::Error under the anyhow feature flag.

Breaking Changes

Notes & open questions

Change checklist

• Self-review.
• Documentation updates following the style guide, if relevant.
• Tests if relevant.
• All breaking changes documented.

[github-actions]

Documentation for this PR has been generated and is available at: https://n0-computer.github.io/n0-error/pr/14/docs/n0_error/

Last updated: 2025-11-11T21:54:04Z

[matheus23]

Needs the module docs under "Feature flags" to be updated to mention the additional implementations you now get with the anyhow feature.

---

Tbh, the anyhow feature has confused me with n0-error so far.
In all our stuff I've basically replaced anyhow! with bail_any! and generally replaced anyhow::Error and anyhow::Result with n0_error::Error and n0_error::Result.

I guess this might be useful for third parties that don't have the luxury of completely getting rid of anyhow.

[Frando]

Yeah, the thing is that anyhow::Error does not implement std::error::Error so without the compat feature the result extensions won't work on anyhow errors, and to go from anyhow to AnyError the way is AnyError::from_std(err.into_boxed_dyn_error()), which is cumbersome.