backup: Use the localrepo.ErrEmptyBundle sentinel

This error indicates that git refused to create an empty bundle. This
sentinel did not exist when backups were originally implemented. Now
that it does we can simplify some of the error handling.

2 files changed, 3 insertions, 9 deletions

diff --git a/internal/backup/backup.go b/internal/backup/backup.go
index 12bc0f730..138e05578 100644
--- a/internal/backup/backup.go
+++ b/internal/backup/backup.go
@@ -26,9 +26,6 @@ var (
 	ErrDoesntExist = errors.New("doesn't exist")
 )
 
-// errEmptyBundle means that the requested bundle contained nothing
-var errEmptyBundle = errors.New("empty bundle")
-
 // Sink is an abstraction over the real storage used for storing/restoring backups.
 type Sink interface {
 	// GetWriter saves the written data to relativePath. It is the callers
@@ -368,7 +365,7 @@ func (mgr *Manager) writeBundle(ctx context.Context, repo Repository, step *Step
 	}()
 
 	if err := repo.CreateBundle(ctx, w, io.MultiReader(negatedRefs, patternReader)); err != nil {
-		if errors.Is(err, errEmptyBundle) {
+		if errors.Is(err, localrepo.ErrEmptyBundle) {
 			return fmt.Errorf("write bundle: %w: no changes to bundle", ErrSkipped)
 		}
 		return fmt.Errorf("write bundle: %w", err)
diff --git a/internal/backup/repository.go b/internal/backup/repository.go
index c21143d8c..5542864b9 100644
--- a/internal/backup/repository.go
+++ b/internal/backup/repository.go
@@ -136,7 +136,7 @@ func (rr *remoteRepository) CreateBundle(ctx context.Context, out io.Writer, pat
 	bundle := streamio.NewReader(func() ([]byte, error) {
 		resp, err := stream.Recv()
 		if structerr.GRPCCode(err) == codes.FailedPrecondition {
-			err = errEmptyBundle
+			err = localrepo.ErrEmptyBundle
 		}
 		return resp.GetData(), err
 	})
@@ -223,10 +223,7 @@ func (r *localRepository) CreateBundle(ctx context.Context, out io.Writer, patte
 	err := r.repo.CreateBundle(ctx, out, &localrepo.CreateBundleOpts{
 		Patterns: patterns,
 	})
-	switch {
-	case errors.Is(err, localrepo.ErrEmptyBundle):
-		return errEmptyBundle
-	case err != nil:
+	if err != nil {
 		return fmt.Errorf("local repository: create bundle: %w", err)
 	}