[Modify] Polish it

websocket-sharp/WebSocket.cs

@@ -2613,7 +2613,11 @@ namespace WebSocketSharp
         throw new ArgumentException (msg, "code");
       }
 
-      if (!reason.IsNullOrEmpty ()) {
+      if (reason.IsNullOrEmpty ()) {
+        close (code, String.Empty);
+        return;
+      }
+
       if (code == 1005) {
         var msg = "1005 cannot be used.";
         throw new ArgumentException (msg, "code");
@@ -2629,7 +2633,6 @@ namespace WebSocketSharp
         var msg = "Its size is greater than 123 bytes.";
         throw new ArgumentOutOfRangeException ("reason", msg);
       }
-      }
 
       close (code, reason);
     }