Remove obsolete DOMContentLoadedEventListener

app/assets/javascripts/pages/projects/feature_flags_user_lists/show/index.js

-import Vue from 'vue';
-import Vuex from 'vuex';
-import UserList from '~/user_lists/components/user_list.vue';
-import createStore from '~/user_lists/store/show';
+import featureFlagsUserListInit from '~/projects/feature_flags_user_lists/show/index';
 
-Vue.use(Vuex);
-
-document.addEventListener('DOMContentLoaded', () => {
-  const el = document.getElementById('js-edit-user-list');
-  return new Vue({
-    el,
-    store: createStore(el.dataset),
-    render(h) {
-      const { emptyStatePath } = el.dataset;
-      return h(UserList, { props: { emptyStatePath } });
-    },
-  });
-});
+featureFlagsUserListInit();

app/assets/javascripts/projects/feature_flags_user_lists/show/index.js

+import Vue from 'vue';
+import Vuex from 'vuex';
+import UserList from '~/user_lists/components/user_list.vue';
+import createStore from '~/user_lists/store/show';
+
+Vue.use(Vuex);
+
+export default function featureFlagsUserListInit() {
+  const el = document.getElementById('js-edit-user-list');
+
+  if (!el) {
+    return null;
+  }
+
+  return new Vue({
+    el,
+    store: createStore(el.dataset),
+    render(h) {
+      const { emptyStatePath } = el.dataset;
+      return h(UserList, { props: { emptyStatePath } });
+    },
+  });
+}