Fix ListBranches to handle empty case (#21921)

routers/api/v1/repo/branch.go

@@ -252,42 +252,50 @@ func ListBranches(ctx *context.APIContext) {
 // "200":
 // "$ref": "#/responses/BranchList"
 
+var totalNumOfBranches int
+var apiBranches []*api.Branch
+
 listOptions := utils.GetListOptions(ctx)
-skip, _ := listOptions.GetStartEnd()
-branches, totalNumOfBranches, err := ctx.Repo.GitRepo.GetBranches(skip, listOptions.PageSize)
-if err != nil {
-ctx.Error(http.StatusInternalServerError, "GetBranches", err)
-return
-}
 
-apiBranches := make([]*api.Branch, 0, len(branches))
-for i := range branches {
-c, err := branches[i].GetCommit()
+if !ctx.Repo.Repository.IsEmpty && ctx.Repo.GitRepo != nil {
+skip, _ := listOptions.GetStartEnd()
+branches, total, err := ctx.Repo.GitRepo.GetBranches(skip, listOptions.PageSize)
 if err != nil {
-// Skip if this branch doesn't exist anymore.
-if git.IsErrNotExist(err) {
-totalNumOfBranches--
-continue
-}
-ctx.Error(http.StatusInternalServerError, "GetCommit", err)
+ctx.Error(http.StatusInternalServerError, "GetBranches", err)
 return
 }
-branchProtection, err := git_model.GetProtectedBranchBy(ctx, ctx.Repo.Repository.ID, branches[i].Name)
-if err != nil {
-ctx.Error(http.StatusInternalServerError, "GetBranchProtection", err)
-return
-}
-apiBranch, err := convert.ToBranch(ctx.Repo.Repository, branches[i], c, branchProtection, ctx.Doer, ctx.Repo.IsAdmin())
-if err != nil {
-ctx.Error(http.StatusInternalServerError, "convert.ToBranch", err)
-return
+
+apiBranches = make([]*api.Branch, 0, len(branches))
+for i := range branches {
+c, err := branches[i].GetCommit()
+if err != nil {
+// Skip if this branch doesn't exist anymore.
+if git.IsErrNotExist(err) {
+total--
+continue
+}
+ctx.Error(http.StatusInternalServerError, "GetCommit", err)
+return
+}
+branchProtection, err := git_model.GetProtectedBranchBy(ctx, ctx.Repo.Repository.ID, branches[i].Name)
+if err != nil {
+ctx.Error(http.StatusInternalServerError, "GetProtectedBranchBy", err)
+return
+}
+apiBranch, err := convert.ToBranch(ctx.Repo.Repository, branches[i], c, branchProtection, ctx.Doer, ctx.Repo.IsAdmin())
+if err != nil {
+ctx.Error(http.StatusInternalServerError, "convert.ToBranch", err)
+return
+}
+apiBranches = append(apiBranches, apiBranch)
 }
-apiBranches = append(apiBranches, apiBranch)
+
+totalNumOfBranches = total
 }
 
 ctx.SetLinkHeader(totalNumOfBranches, listOptions.PageSize)
 ctx.SetTotalCountHeader(int64(totalNumOfBranches))
-ctx.JSON(http.StatusOK, &apiBranches)
+ctx.JSON(http.StatusOK, apiBranches)
 }
 
 // GetBranchProtection gets a branch protection