ErrPackageNotFound means the package is not found
DecoratorResolver resolves an identifier to a local or remote reference.
Returns path == "" if the node is not a local or remote reference (e.g. a field in a composite literal, the selector in a selector expression etc.).
Returns path == "" is the node is a local reference.
Returns path != "" is the node is a remote reference.
RestorerResolver resolves a package path to a package name.