One distinction that is often made by core team members is that you only need to annotate errors at package boundaries, and that returning unannotated errors wi

One distinction that is often made by core team members is that you only need to annotate errors at package boundaries, and that returning unannotated errors within a package is fine. But in most code, the packages are not so well-defined, or well-thought-out, or sacrosanct, that they represent a good proxy for annotation decisions. I would much rather have an error with too much or duplicate annotation than one with not enough. And I would further argue that, yes, in the stdlib, errors are generally under-annotated.