Show error box / bar / message when offline

[joepio]

When the client does not have an internet connection, various errors might occur that could confuse the user. Instead of adding "this might be because your internet connection is offline", I'll use the browsers API to check connection status and show a warning when offline.

https://levelup.gitconnected.com/useonlinestatus-a-react-hook-to-know-when-your-app-is-offline-2d06e4e536a