Can anyone tell me whats wrong in this code?

```
void onPressed() async {
    //Navigator.pushNamed(context, "/screen2", arguments: []);
    var receivePort = ReceivePort();
    await Isolate.spawn(gotoNext, [receivePort.sendPort]);
    final msg = await receivePort.first;
    print(msg);
  }

  void gotoNext(List<dynamic> args) {
    SendPort sendPort = args[0];
    log(args.toString());
    Isolate.exit(sendPort, "OK");
  }

```

> 
> E/flutter (12062): [ERROR:flutter/lib/ui/ui\_dart\_state.cc(209)] Unhandled Exception: Invalid argument(s): Illegal argument in isolate message: (object extends NativeWrapper - Library:'dart:ui' Class: Path)
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