[Modify] Throw exceptions

websocket-sharp/WebSocket.cs

@@ -2773,16 +2773,14 @@ namespace WebSocketSharp
     /// </param>
     public void SendAsync (byte[] data, Action<bool> completed)
     {
-      var msg = _readyState.CheckIfAvailable (false, true, false, false) ??
-                CheckSendParameter (data);
-
-      if (msg != null) {
-        _logger.Error (msg);
-        error ("An error has occurred in sending data.", null);
-
-        return;
+      if (_readyState != WebSocketState.Open) {
+        var msg = "The current state of the connection is not Open.";
+        throw new InvalidOperationException (msg);
       }
 
+      if (data == null)
+        throw new ArgumentNullException ("data");
+
       sendAsync (Opcode.Binary, new MemoryStream (data), completed);
     }