Several improvements to error handling:
- Introduce ImageConfigPullError type, wrapping errors related to
downloading the image configuration blob in schema2. This allows for a
more descriptive error message to be seen by the end user.
- Change some logrus.Debugf calls that display errors to logrus.Errorf.
Add log lines in the push/pull fallback cases to make sure the errors
leading to the fallback are shown.
- Move error-related types and functions which are only used by the
distribution package out of the registry package.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
8f26fe4f59