There's a lot of comments here that seem overly critical. The author came up with solutions to extend Go's errors to meet their needs and shared that with the world- thank you.

I have been solving all the same problems and providing libraries that allow for more flexibility so that users can come up with approaches that best meet their needs. I am finally polishing the libraries and starting to write about them:

https://blog.gregweber.info/blog/go-errors-library/ (errors with stack traces and metadata)

https://github.com/gregwebs/errcode (adding codes to errors- working on improving docs and writing about this now).