SendAsync was using InvokeCoreAsync code to send messages. In case of exception InvokeCoreAsync is blocking and returns a task to the user so they can await for the remote call to complete. Any exception thrown is caught and used to fail the task returned to the user. SendAsync does not return a special task to the user so re-using InvokeCore resulted in swallowing exceptions. While SendAsync is fire and forget it actually should throw if the message could not be send and it was not happening.
While adding tests it turned out we did not test cases where Invoke/SendAsync/StreamAsync were invoked before starting the connection and this resulted in a NullReferenceException. I also fixed that.
- Preventing from closing long polling transport with 204 in case of
error
- Reporting an error to the client if WebSocket was not closed normally
Note in case of ServerSentEvents it is not possible on the client to
tell the difference between when the server closed event stream due to
an exception or because the client left OnConnectedAsync. In both cases
the client sees only that the stream was closed.
Part of: #163