fix: revert tab name and improve group list error handling

backend/internal/service/user_group_service.go

@@ -192,12 +192,19 @@ func (s *userGroupService) List(ctx context.Context, tenantID string) ([]domain.
 		return nil, err
 	}
 
+	if s.ketoService == nil {
+		return groups, nil
+	}
+
 	// For each group, fetch member count from Keto
 	for i := range groups {
 		tuples, err := s.ketoService.ListRelations(ctx, "Tenant", groups[i].ID, "members", "")
 		if err == nil {
 			// Create dummy members just to carry the count for the JSON response
 			groups[i].Members = make([]domain.User, len(tuples))
+		} else {
+			slog.Warn("Failed to fetch member count from Keto", "groupID", groups[i].ID, "error", err)
+			groups[i].Members = []domain.User{}
 		}
 	}