Add "errors" package
This is a thin wrapper over the `pkg/errors` package. It decorates the
base package with the following functionality:
1. Wrap and Wrapf produce an error with exactly one stack trace. If
the wrapped error already contains a stack trace, these functions just
append text to the message.
2. WithStack produces an error with exactly one stack trace. If the
wrapped error already contains a stack trace, it is returned unmodified.
All of artifact's public APIs return errors produced with this package.
This allows us to remove the dependency on newt (`NewtError`) but still
retain error stack traces.
1 file changed
