github.com/speijnik/go-errortree (go): Package errortree provides primitives for working with errors in tree structure  errortree is intended to be used in places where errors are generated from an arbitrary tree structure, like the validation of a configuration file. This allows adding additional context as to why an error has happened in a clean and structured way.  errortree fully supports nesting of multiple trees, including simplified retrieval of errors which, among other things, should help remove repeated boilerplate code from unit tests.
Keywords: error|error-handling|go|golang