As of version 2.12.8 of MediaWikiChat the config option $wgChatSocialAvatars is set to true per default. This causes an empty chatroom to appear in installations without SocialProfile Extension The problem is described in the extensions's discussion page and can be reproduced with current stable MediaWiki 1.24.2.
Possible solutions:
- add SocialProfile as a dependency
- set $wgChatSocialAvatars to "false" by default
- give advice in documentation