When attempting to access the conpherwnce an I handled exception occurs for Undefined variable: theme_class.
Reproduction:
1. As a logged out user, that is not a member of any rooms, access the homepage of secure.phabricator.com
2. Select the link to general chat
3. Get exception message
In ConpherenceThread.phpon line 213 theme_class is only set if the user is a participant, but the theme_class variable is accessed even if user is not in the room.
Version:
Phabricator: 3698e4a14f6c