Unhandled Exception under Xamarin iOS

I'm using ssh.net in a Xamarin iOS application. When connecting to a sftp server with the iOS 's wifi turn off. I got this exception:
Unhandled Exception:
System.ObjectDisposedException: Safe handle has been closed occurred.
I debug the source code and found out that's because under Xamarin iOS
socket.ConnectAsync(args) return false when wifi is turned off.
SocketAbstraction.cs line 63 if (socket.ConnectAsync(args))
Then it run line 83 connectCompleted.Dispose();
At last function ConnectCompleted was called , where the exception occurred.

If I moved line 83 connectCompleted.Dispose() into below if statement like this:

       if (args.SocketError != SocketError.Success)
        {
            var socketError = (int) args.SocketError;

            // dispose Socket
            socket.Dispose();
            // dispose SocketAsyncEventArgs
            args.Dispose();

            // dispose ManualResetEvent
            connectCompleted.Dispose();

            throw new SocketException(socketError);
        }

then this bug is fixed.

Inizia in SocketAbstraction.cs intorno alla riga 63, dove viene gestito socket.ConnectAsync(args), e alla riga 83, dove viene eliminato connectCompleted. Riproduci la connessione SFTP di Xamarin iOS con il Wi-Fi disabilitato e traccia ConnectCompleted. Il lavoro è completato quando la connessione fallita genera l'errore socket previsto senza una ObjectDisposedException.