SignalR core (preview2) exception when client disconnects.

exception.cs

[14:57:27 ERR] The remote party closed the WebSocket connection without completing the close handshake.
System.Net.WebSockets.WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
   --- End of inner exception stack trace ---
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error)
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.GetResult(Int16 token)
   at System.Net.Http.HttpConnection.ReadBufferedAsyncCore(Memory`1 destination)
   at System.Net.Http.HttpConnection.RawConnectionStream.ReadAsync(Memory`1 buffer, CancellationToken cancellationToken)
   at System.Net.WebSockets.ManagedWebSocket.EnsureBufferContainsAsync(Int32 minimumRequiredBytes, Boolean throwOnPrematureClosure)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TWebSocketReceiveResultGetter,TWebSocketReceiveResult](Memory`1 payloadBuffer, CancellationToken cancellationToken, TWebSocketReceiveResultGetter resultGetter)
   at System.Net.WebSockets.ManagedWebSocket.ReceiveAsyncPrivate[TWebSocketReceiveResultGetter,TWebSocketReceiveResult](Memory`1 payloadBuffer, CancellationToken cancellationToken, TWebSocketReceiveResultGetter resultGetter)
   at Microsoft.AspNetCore.Http.Connections.Client.Internal.WebSocketsTransport.StartReceiving(WebSocket socket)
   at System.IO.Pipelines.PipeCompletion.ThrowLatchedException()
   at System.IO.Pipelines.Pipe.GetReadResult(ReadResult& result)
   at System.IO.Pipelines.Pipe.GetReadAsyncResult()
   at System.IO.Pipelines.Pipe.DefaultPipeReader.GetResult(Int16 token)
   at Microsoft.AspNetCore.SignalR.Client.HubConnection.ReceiveLoop(ConnectionState connectionState)