It's true that the preferred idiomatic approach to implementing error types hasn't stabilized. However, that "churn" has all been in third-party crates, so > a

It's true that the preferred idiomatic approach to implementing error types hasn't stabilized. However, that "churn" has all been in third-party crates, so > a lot of this churn could have happened "in userspace": different approaches to async or error handling would be library changes rather than language changes. is exactly what has been happening, for error handling.