Merge branch '322724-fix-compare-page-dropdown-loading' into 'master'

Fix issue with loading tags on the compare page

See merge request gitlab-org/gitlab!55058

app/assets/javascripts/projects/compare/components/revision_dropdown_legacy.vue

@@ -65,8 +65,8 @@ export default {
       return axios
         .get(endpoint)
         .then(({ data }) => {
-          this.branches = data.Branches;
-          this.tags = data.Tags;
+          this.branches = data.Branches || [];
+          this.tags = data.Tags || [];
         })
         .catch(() => {
           createFlash({

changelogs/unreleased/322724-fix-compare-page-dropdown-loading.yml

+---
+title: Fix issue with loading the repository compare page
+merge_request: 55058
+author:
+type: fixed

spec/frontend/projects/compare/components/revision_dropdown_legacy_spec.js

@@ -62,6 +62,20 @@ describe('RevisionDropdown component', () => {
     expect(wrapper.vm.tags).toEqual(Tags);
   });
 
+  it('sets branches and tags to be an empty array when no tags or branches are given', async () => {
+    axiosMock.onGet(defaultProps.refsProjectPath).replyOnce(200, {
+      Branches: undefined,
+      Tags: undefined,
+    });
+
+    createComponent();
+
+    await axios.waitForAll();
+
+    expect(wrapper.vm.branches).toEqual([]);
+    expect(wrapper.vm.tags).toEqual([]);
+  });
+
   it('shows flash message on error', async () => {
     axiosMock.onGet('some/invalid/path').replyOnce(404);