Subscribing to private messages is broken

[shepwalker]

Using the Slack Adapter for Hubot, whenever I try to subscribe to an event via a private message, the emit fails.

Debug messages:

[Thu Jun 11 2015 21:36:15 GMT+0000 (Coordinated Universal Time)] DEBUG Sending to C02FZLYR6: testevent1: blerg
[Thu Jun 11 2015 21:36:17 GMT+0000 (Coordinated Universal Time)] ERROR TypeError: Cannot call method 'send' of undefined
  at SlackBot.send (D:\home\site\wwwroot\node_modules\hubot-slack\src\slack.coffee:206:17)
  at Robot.send (D:\home\site\wwwroot\node_modules\hubot\src\robot.coffee:404:5)
  at notify (D:\home\site\wwwroot\node_modules\hubot-pubsub\src\pubsub.coffee:67:15)
  at TextListener.callback (D:\home\site\wwwroot\node_modules\hubot-pubsub\src\pubsub.coffee:132:13)
  at TextListener.Listener.call (D:\home\site\wwwroot\node_modules\hubot\src\listener.coffee:27:8)
  at Robot.receive (D:\home\site\wwwroot\node_modules\hubot\src\robot.coffee:197:31)
  at SlackBot.Adapter.receive (D:\home\site\wwwroot\node_modules\hubot\src\adapter.coffee:66:12)
  at SlackBot.message (D:\home\site\wwwroot\node_modules\hubot-slack\src\slack.coffee:154:8)
  at Client.<anonymous> (D:\home\site\wwwroot\node_modules\hubot-slack\src\slack.coffee:1:1)
  at Client.emit (events.js:95:17)
  at Client.onMessage (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\src\client.js:477:14)
  at WebSocket.<anonymous> (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\src\client.js:140:24)
  at WebSocket.emit (events.js:98:17)
  at Receiver.self._receiver.ontext (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\node_modules\ws\lib\WebSocket.js:697:10)
  at Receiver.opcodes.1.finish (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\node_modules\ws\lib\Receiver.js:397:14)
  at Receiver.expectHandler (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\node_modules\ws\lib\Receiver.js:384:31)
  at Receiver.add (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\node_modules\ws\lib\Receiver.js:93:24)
  at CleartextStream.firstHandler (D:\home\site\wwwroot\node_modules\hubot-slack\node_modules\slack-client\node_modules\ws\lib\WebSocket.js:678:22)
  at CleartextStream.emit (events.js:95:17)
  at CleartextStream.<anonymous> (_stream_readable.js:764:14)
  at CleartextStream.emit (events.js:92:17)
  at emitReadable_ (_stream_readable.js:426:10)
  at _stream_readable.js:419:7
  at process._tickCallback (node.js:419:13)

Trying my hand at coffeescript debugging to understand what's going on but haven't had much luck.

[spajus]

From the stack trace it fails when performing robot.send(user, message). Got to investigate how Slack adapter handles private messages.