[Feature Reguest] Error trait

[Iizuki]

Summary

Could we add an Error implementation to EitherOrBoths where both type parameters implement Error themselves? Similar to the either crate.

A little care would have to be taken to clearly indicate the variant in the error messages etc.

Use cases

This would allow EitherOrBoths to compose better with other Result/Error types, e.g. when using anyhow. Although the existing transpose methods are a great help already.

PS

This is a neat crate with a plethora of niceties already implemented!