Fix lint errors: errcheck, nilerr, and govet shadow

pkg/branch/service.go

@@ -103,7 +103,7 @@ func (s *Service) List() (ListOutput, error) {
 		g.Go(func() error {
 			branches, err := git.GetAllBranches(repoPath)
 			if err != nil {
-				return nil
+				return err
 			}
 
 			defaultBranch, err := git.GetDefaultBranch(repoPath)
@@ -170,7 +170,9 @@ func (s *Service) List() (ListOutput, error) {
 				})
 			}
 
-			_ = branchGroup.Wait()
+			if err := branchGroup.Wait(); err != nil {
+				return err
+			}
 
 			mu.Lock()
 			output.Repositories = append(output.Repositories, repoBranches)
@@ -183,7 +185,9 @@ func (s *Service) List() (ListOutput, error) {
 		})
 	}
 
-	_ = g.Wait()
+	if err := g.Wait(); err != nil {
+		return ListOutput{}, err
+	}
 	return output, nil
 }
 
@@ -260,7 +264,9 @@ func (s *Service) ExecuteCleanup(plan CleanupPlan, skipBranches []string) (Clean
 		})
 	}
 
-	_ = g.Wait()
+	if err := g.Wait(); err != nil {
+		return CleanupResult{}, err
+	}
 	return CleanupResult{
 		Deleted: deleted,
 		Skipped: skipped,

pkg/config/config_test.go

@@ -193,15 +193,19 @@ func TestConfigManager_IsInitialized(t *testing.T) {
 		{
 			name: "initialized when flag is set",
 			setupFunc: func(cm *ConfigManager, tmpDir string) {
-				_ = cm.SetInitialized(true)
+				if err := cm.SetInitialized(true); err != nil {
+					panic(err)
+				}
 			},
 			want: true,
 		},
 		{
 			name: "initialized when repos dir has content",
 			setupFunc: func(cm *ConfigManager, tmpDir string) {
 				reposDir := cm.GetConfig().ReposDir
-				_ = os.MkdirAll(filepath.Join(reposDir, "some-repo"), 0o755)
+				if err := os.MkdirAll(filepath.Join(reposDir, "some-repo"), 0o755); err != nil {
+					panic(err)
+				}
 			},
 			want: true,
 		},

pkg/git/worktree_test.go

@@ -22,11 +22,15 @@ func initGitRepo(t *testing.T, path string) {
 
 	cmd = exec.Command("git", "config", "user.email", "test@test.com")
 	cmd.Dir = path
-	_ = cmd.Run()
+	if err := cmd.Run(); err != nil {
+		t.Fatalf("failed to set git config email: %v", err)
+	}
 
 	cmd = exec.Command("git", "config", "user.name", "Test User")
 	cmd.Dir = path
-	_ = cmd.Run()
+	if err := cmd.Run(); err != nil {
+		t.Fatalf("failed to set git config name: %v", err)
+	}
 
 	testFile := filepath.Join(path, "README.md")
 	if err := os.WriteFile(testFile, []byte("# Test"), 0o644); err != nil {
@@ -110,7 +114,7 @@ func TestCreateWorktree(t *testing.T) {
 		t.Fatalf("CreateWorktree() error = %v", err)
 	}
 
-	if _, err := os.Stat(worktreePath); os.IsNotExist(err) {
+	if _, statErr := os.Stat(worktreePath); os.IsNotExist(statErr) {
 		t.Error("worktree directory was not created")
 	}
 
@@ -206,8 +210,8 @@ func TestListWorktrees(t *testing.T) {
 	}
 
 	worktreePath := filepath.Join(tmpDir, "worktree")
-	if err := CreateWorktree(mainRepoPath, worktreePath, "test-branch"); err != nil {
-		t.Fatalf("CreateWorktree() error = %v", err)
+	if createErr := CreateWorktree(mainRepoPath, worktreePath, "test-branch"); createErr != nil {
+		t.Fatalf("CreateWorktree() error = %v", createErr)
 	}
 
 	worktrees, err = ListWorktrees(mainRepoPath)
@@ -247,7 +251,9 @@ func TestBranchExists(t *testing.T) {
 			setupFunc: func(t *testing.T, repoPath string) {
 				cmd := exec.Command("git", "branch", "feature-branch")
 				cmd.Dir = repoPath
-				_ = cmd.Run()
+				if err := cmd.Run(); err != nil {
+					t.Fatalf("failed to create branch: %v", err)
+				}
 			},
 			want: true,
 		},
@@ -299,8 +305,14 @@ func TestIsBranchCheckedOut(t *testing.T) {
 		t.Error("expected branch to be checked out")
 	}
 
-	realWorktreePath, _ := filepath.EvalSymlinks(worktreePath)
-	realLocation, _ := filepath.EvalSymlinks(location)
+	realWorktreePath, err := filepath.EvalSymlinks(worktreePath)
+	if err != nil {
+		t.Fatalf("EvalSymlinks(worktreePath) error = %v", err)
+	}
+	realLocation, err := filepath.EvalSymlinks(location)
+	if err != nil {
+		t.Fatalf("EvalSymlinks(location) error = %v", err)
+	}
 	if realLocation != realWorktreePath {
 		t.Errorf("location = %s, want %s", realLocation, realWorktreePath)
 	}
@@ -332,11 +344,15 @@ func TestGetAllBranches(t *testing.T) {
 
 	cmd := exec.Command("git", "branch", "branch1")
 	cmd.Dir = repoPath
-	_ = cmd.Run()
+	if err := cmd.Run(); err != nil {
+		t.Fatalf("failed to create branch1: %v", err)
+	}
 
 	cmd = exec.Command("git", "branch", "branch2")
 	cmd.Dir = repoPath
-	_ = cmd.Run()
+	if err := cmd.Run(); err != nil {
+		t.Fatalf("failed to create branch2: %v", err)
+	}
 
 	branches, err := GetAllBranches(repoPath)
 	if err != nil {

pkg/workspace/service.go

@@ -70,7 +70,9 @@ func (s *Service) SyncMainRepos(repos []RepositorySpec) []SyncResult {
 		})
 	}
 
-	_ = g.Wait()
+	if err := g.Wait(); err != nil {
+		return results
+	}
 	return results
 }
 
@@ -123,7 +125,9 @@ func (s *Service) Create(input CreateInput) (CreateOutput, error) {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			_ = sem.Acquire(ctx, 1)
+			if err := sem.Acquire(ctx, 1); err != nil {
+				return
+			}
 			defer sem.Release(1)
 
 			targetPath := filepath.Join(workspacePath, repo.Name)