Fix dismissable_callout import

app/assets/javascripts/dismissable_callout.js

+import PersistentUserCallout from './persistent_user_callout';
+
+export default function initDismissableCallout(alertSelector) {
+  const alertEl = document.querySelector(alertSelector);
+  if (!alertEl) {
+    return;
+  }
+
+  new PersistentUserCallout(alertEl); // eslint-disable-line no-new
+}