Rust: Enums to wrap multiple errors

https://fettblog.eu/rust-enums-wrapping-errors/ · This is a follow-up to Error handling in Rust from a couple of days ago. The moment we want to use error propagation for different error types, we have to rely on trait objects with Box<dyn Error>, which means we defer a lot of information from compile-time to runtime, for the sake of convenient error handling.