Internal error when accessing plugin configuration

[itatabitovski]

I am running

• redmine 2.4.1 (commit 092499633631416782454cbe405f75399d87d2a9)
• redmine_hipchat (commit 2246343)

Plugin migration worked OK

Migrating redmine_hipchat (HipChat)...
==  AddHipChatTokenAndRoomIdToProject: migrating ==============================
-- add_column(:projects, :hipchat_auth_token, :string, {:default=>"", :null=>false})
   -> 0.0861s
-- add_column(:projects, :hipchat_room_name, :string, {:default=>"", :null=>false})
   -> 0.0158s
-- add_column(:projects, :hipchat_notify, :boolean, {:default=>false, :null=>false})
   -> 0.0218s
==  AddHipChatTokenAndRoomIdToProject: migrated (0.1243s) =====================

Redmine is restarted and this error is in the log

Started GET "/settings/plugin/redmine_hipchat" for 84.128.170.240 at 2014-11-24 08:36:44 +0000
Processing by SettingsController#plugin as HTML
  Parameters: {"id"=>"redmine_hipchat"}
  Current user: drose (id=92)
Completed 500 Internal Server Error in 4.0ms

Any ideas?