Fix notification panel filtering and sorting

Author: rvsia

packages/react-renderer-demo/src/app/src/components/notification-panel.js

@@ -40,7 +40,7 @@ const getNotifications = () => {
   const query = `?orderBy="expired-at"&startAt="${new Date().toISOString()}"&limitToFirst=10`;
   return fetch(`https://data-driven-forms.firebaseio.com/notifications.json${query}`)
     .then((data) => data.json())
-    .then((data) => data || []);
+    .then((data) => data.filter(Boolean).sort((a, b) => b['created-at'].localeCompare(a['created-at'])) || []);
 };
 
 const createNotificationId = (notification) => `${notification['created-at']}-${notification['expired-at']}`;