Dblog module uses LEFT JOIN on the users table to select log entries on the overview display, but INNER JOIN to select on the detail display.
This results in log entries visible on the overview page that result in a blank display when viewing the entry detail for a user that has been deleted.
Usually, this would be a very minor issue, but on one of our sites, users are ephemeral for legal reasons - ie users are created on-the-fly from
the response of a secure webservice, and deleted on logout/timeout from the database. Of course this makes viewing log messages awkward after the user has logged out. LEFT JOIN returns a NULL uid from the users table and allows viewing log messages for deleted users as coming from anonymous.
Trivial patch follows to use LEFT JOIN on the dblog detail view.