Add check in repo compare when data is undefined

app/assets/javascripts/projects/compare/components/revision_dropdown.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/320836-display-compare-button.yml

+---
+title: Safe guard repo compare when data is undefined
+merge_request: 54371
+author:
+type: fixed