Update api.js group to make callback optional

app/assets/javascripts/api.js

@@ -52,7 +52,7 @@ const Api = {
   environmentsPath: '/api/:version/projects/:id/environments',
   rawFilePath: '/api/:version/projects/:id/repository/files/:path/raw',
 
-  group(groupId, callback) {
+  group(groupId, callback = () => {}) {
     const url = Api.buildUrl(Api.groupPath).replace(':id', groupId);
     return axios.get(url).then(({ data }) => {
       callback(data);

ee/app/assets/javascripts/audit_events/components/tokens/group_token.vue

@@ -9,7 +9,7 @@ export default {
   inheritAttrs: false,
   tokenMethods: {
     fetchItem(id) {
-      return Api.group(id, () => {});
+      return Api.group(id);
     },
     fetchSuggestions(term) {
       return Api.groups(term);