Which to be clear, is a language design mistake. Go would be a much more productive and friendly language if errors would just have stack traces on them when they're created. There's no reason to have the poor developer adding dozens of debug prints all over his (and sometimes third-party) code manually into every place that could have returned the error just to try and discern where it comes from. Or grepping for strings in the error message, or throwing darts at printouts of the source. That's just a massive step backwards from what we've had since the 80s and 90s. I know Go prides itself on being simple, but really the errors are too simple and we're all worse off because of it.
The problem is that Go errors are just a convention, they are not a feature of Go. It's just an interface, it could have been called FOO it wouldn't have made a difference. Go has exceptions, they are called "panic" by they are inferior to Java in the way they are handled.
I know they're just a convention, but that was a mistake. It should have had more first-class language support so that they have stacktraces at least.
I'm seriously beginning to think that even with the limitations, panic is a better error handling mechanism for all exceptional error cases. At least it has stacktraces and doesn't clutter the code with error boilerplate. I don't think I'd be able to convince anyone of that on a real project though, I'd have to try it on a personal project.