Since the changes performed by
MDL-29602 happened, user contexts are not created anymore for deleted users.
This leads, since some weeks ago (2.2dev) to the user/view.php page (and perhaps others using the user context too) returning early (red) errors associated with that context not being available.
The page also contains one special output for deleted changes some lines below, but it is never executed due to the early error.
More yet, ideally, IMO, we should NOT provide links to the pages of deleted users in practically any place.