github.com/m-zajac/verrors (go): Package verrors provides simple helpers for creating errors, which can be checked for their "traits".  Package exposes only 2 functions: "WithValue" and "Value", which helps creating error constructors and trait checks.  This package is created as extension of github.com/pkg/errors, but pkg/errors is not required. You can wrap errors by errors.Wrap and trait checks will still work.  Example:
Keywords: error-handling|errors|golang