Comment by ndriscoll

Usually in Scala errors subtype Throwable, so as long as new union members continue to do so, if you wanted a generic handler (e.g. you just log and return) you could handle that. But you can also be more specific with actual logic, with the benefit that if you choose to do so and the underlying implementation changes, you detect it.

Go also basically requires you to write actually generic error code (if err != nil return err), so it feels like errors are more work than they are. In Scala (especially ZIO) propagation is all automatic and you just handle it wherever you'd like. The only code that cares about errors is the part generating them and the part handling them. But it's all tracked in the type system so you can always see what exact errors are possible from what methods. And it's all simple return values so no trickiness with exceptions (e.g. across async boundaries).