In several instances the system displays the Error: Cannot read property 'message' of null; rather than redirecting the user to the Login Screen after a session timeout (of clearing your cache in a different browser window).
This, along with the typical timeout occurring, produces unexpected results when logging back in. This was reported as a bug but were told:

The system does not inform the user that the session is approaching timeout or that the session ended. Sadly, that is is the limitation of the current design.