refactor(syncer): drop unused Err field from failed repo records

failedRepo carried both the repo path and the error returned by the
git invocation, but the error field was never read after assignment.
The per-repo failure reason is already streamed to stderr at execution
time via PrintMsgErr ("Failed: <repo>\n<err>"), and printSummary only
needs the repo path to print the trailing failed-repo list.

Replace the failedRepo struct with a plain []string and update
addFailed and the summary printer accordingly. The test that asserted
on stats.failed[0].Repo becomes stats.failed[0] — same coverage,
slightly cleaner.

Reported by GitHub Copilot on PR #26.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: takecy

syncer/syncer.go

@@ -55,18 +55,14 @@ type Sync struct {
 	Gitter Executor
 }
 
-// failedRepo carries the repository path together with the error that caused
-// the failure so that it can be reported in the final summary.
-type failedRepo struct {
-	Repo string
-	Err  error
-}
-
 // runStats accumulates per-repository outcomes safely from concurrent goroutines.
+// Each bucket is just a list of repository paths — the per-repo error message
+// is already streamed to stderr at execution time via PrintMsgErr, so there is
+// no need to retain it here.
 type runStats struct {
 	mu        sync.Mutex
 	succeeded []string
-	failed    []failedRepo
+	failed    []string
 	timedOut  []string
 }
 
@@ -76,10 +72,10 @@ func (s *runStats) addSuccess(r string) {
 	s.succeeded = append(s.succeeded, r)
 }
 
-func (s *runStats) addFailed(r string, e error) {
+func (s *runStats) addFailed(r string) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	s.failed = append(s.failed, failedRepo{Repo: r, Err: e})
+	s.failed = append(s.failed, r)
 }
 
 func (s *runStats) addTimedOut(r string) {
@@ -203,7 +199,7 @@ func (s *Sync) execute(parent context.Context, repos []string, perRepoTimeout ti
 				stats.addTimedOut(r)
 				s.Writer.PrintMsgErr(fmt.Sprintf("Timeout: %s", r))
 			default:
-				stats.addFailed(r, err)
+				stats.addFailed(r)
 				s.Writer.PrintMsgErr(fmt.Sprintf("Failed: %s\n%v", r, err))
 			}
 
@@ -245,11 +241,7 @@ func (s *Sync) printSummary(stats *runStats) {
 	))
 
 	if len(stats.failed) > 0 {
-		repos := make([]string, len(stats.failed))
-		for i, f := range stats.failed {
-			repos[i] = f.Repo
-		}
-		s.Writer.PrintRepoErr("Failed repositories:", repos)
+		s.Writer.PrintRepoErr("Failed repositories:", stats.failed)
 	}
 	if len(stats.timedOut) > 0 {
 		s.Writer.PrintRepoErr("Timed out repositories:", stats.timedOut)

syncer/syncer_test.go

@@ -59,7 +59,7 @@ func TestSync_Execute(t *testing.T) {
 		stats := s.execute(context.Background(), []string{"a", "b", "c"}, time.Second)
 		is.Equal(len(stats.succeeded), 2)
 		is.Equal(len(stats.failed), 1)
-		is.Equal(filepath.Base(stats.failed[0].Repo), "b")
+		is.Equal(filepath.Base(stats.failed[0]), "b")
 	})
 
 	t.Run("timeout is classified separately", func(t *testing.T) {