With that example, since you use `Result::map_err` and specify the specific variant, you aren't really using anything from thiserror at the site of the `?`, correct?
Most usages I have seen, people use `#[from]`, which would end up having conflicting implementations. Is there a reason you didn't use `#[from]` for `ParseConfig`?
In short, I consider `From::from` implementations for errors to be an anti-pattern. It is super easy to become lax about adding context with these implementations in place. Especially as code is modified in the future.
I describe the approach that I use for errors in a detail in an article (https://kazlauskas.me/entries/errors.html) that has already been linked elsewhere in the thread. It is, as far as I can tell, pretty much equivalent to what `snafu` makes users to do.