Revisit Error handling: don't return `miette::Result` from low-level types

[xfbs]

Look into the error handling discussions and see if it is really necessary to return miette::Result from low-level implementations (such as FromStr) and methods.

My general feeling is that this is not the right thing to do, but there has been some previous discussion about it that I need to catch up. If the current approach is correct, I will close this issue.