[Modify] Polish it

websocket-sharp/Server/HttpServer.cs

@@ -1038,11 +1038,13 @@ namespace WebSocketSharp.Server
       }
       catch (Exception ex) {
         var msg = "The underlying listener has failed to start.";
+
         throw new InvalidOperationException (msg, ex);
       }
 
       _receiveThread = new Thread (new ThreadStart (receiveRequest));
       _receiveThread.IsBackground = true;
+
       _receiveThread.Start ();
     }