InvalidEncoding representation

[dtolnay]

It looks like this is used for a very limited set of situations. It should be possible to represent them in a nicer way than { desc: &'static str, detail: Option<String> }.

InvalidEncoding {
    desc: "string was not valid utf8",
    detail: None,
}
InvalidEncoding {
    desc: "error while decoding utf8 string",
    detail: Some(format!("Deserialize error: {}", err))
}
InvalidEncoding {
    desc: "invalid u8 when decoding bool",
    detail: Some(format!("Expected 0 or 1, got {}", value))
}
InvalidEncoding {
    desc: "Invalid char encoding",
    detail: None,
}
InvalidEncoding {
    desc: "invalid tag when decoding Option",
    detail: Some(format!("Expected 0 or 1, got {}", value))
}

Maybe something like:

InvalidUtf8
also InvalidUtf8...?
InvalidBool
InvalidChar
InvalidOption

with the relevant information in each case to build the error message.