> Rust was designed smarter from the start

I guess this makes it pretty clear that there's no useful conversation to be had with you on this topic.

> (In point of fact you shouldn't use fmt.Errorf if you're serious about errors either; it cannot be usefully inspected at runtime. You want an explicitly declared error type for that.)

You don't need a discrete error type to allow callers to inspect returned errors at runtime -- `fmt.Errorf("annotation: %w", err)` allows callers to check for sentinel errors via `errors.Is` -- which is the overwhelmingly most common case.