chore: adds a check to only query reactions when there are actual memos (#4984)

server/router/api/v1/memo_service.go

@@ -186,6 +186,7 @@ func (s *APIV1Service) ListMemos(ctx context.Context, request *v1pb.ListMemosReq
 		memoNames = append(memoNames, fmt.Sprintf("'%s/%s'", MemoNamePrefix, m.UID))
 	}
 
+	if len(memoNames) > 0 {
 		reactions, err := s.Store.ListReactions(ctx, &store.FindReaction{
 			Filters: []string{fmt.Sprintf("content_id in [%s]", strings.Join(memoNames, ", "))},
 		})
@@ -196,6 +197,7 @@ func (s *APIV1Service) ListMemos(ctx context.Context, request *v1pb.ListMemosReq
 		for _, reaction := range reactions {
 			reactionMap[reaction.ContentID] = append(reactionMap[reaction.ContentID], reaction)
 		}
+	}
 
 	for _, memo := range memos {
 		name := fmt.Sprintf("'%s/%s'", MemoNamePrefix, memo.UID)