Getting System.NullReferenceException at PhoenixChannels.Socket.FlushSendBuffer() using the example under Phoenix 1.4.11

[acrolink]

Here is the error at VS:

System.NullReferenceException
  HResult=0x80004003
  Message=Object reference not set to an instance of an object.
  Source=PhoenixChannels
  StackTrace:
   at PhoenixChannels.Socket.FlushSendBuffer()

And here are what gets received at the Phoenix back-end:

[info] CONNECTED TO MemeWeb.UserSocket in 192µs
  Transport: :websocket
  Serializer: Phoenix.Socket.V2.JSONSerializer
  Connect Info: %{}
  Parameters: %{"vsn" => "2.0.0"}