Feedback from failed API Calls in the UI

[sphenlee]

If an API call in the UI fails (eg. the authentication proxy returns 403) no feedback is given to the user.

For forbidden errors:

• A warning like "You have been logged out, please refresh the page" OR
• Redirect back to the login page automatically

For other errors:

• "Something went wrong, please refresh or try again later" ?
• Maybe something else?

This behaviour should probably depend on what the authn proxy does (ie. does it return a redirect or a forbidden?)