[Modify] Polish it

websocket-sharp/WebSocket.cs

@@ -2765,17 +2765,20 @@ namespace WebSocketSharp
         throw new ArgumentOutOfRangeException ("code", msg);
       }
 
-      if (_client && code == 1011) {
+      if (_client) {
+        if (code == 1011) {
           var msg = "1011 cannot be used.";
 
           throw new ArgumentException (msg, "code");
         }
-
-      if (!_client && code == 1010) {
+      }
+      else {
+        if (code == 1010) {
           var msg = "1010 cannot be used.";
 
           throw new ArgumentException (msg, "code");
         }
+      }
 
       if (reason.IsNullOrEmpty ()) {
         close (code, String.Empty);