Electron Version: 7.1.1
Operating System: Windows 10 (1803)

If I set the 'margins' option when call webContents.print method,
The app will crash with no error message.

```js
let { remote } = require("electron");
let webContents = remote.getCurrentWebContents();
webContents.print(
  {
    margins: {
      marginType: "custom",
      top: 30,
      bottom: 0,
      left: 0,
      right: 0
    }
  },
  (success, errorType) => {
    if (!success) console.log(errorType);
  }
);
```

shell/browser/api/electron_api_web_contents.cc
&electron_renderer);
    electron_renderer->Message(internal, false, channel, args.ShallowClone(),
                               sender_id);
  }
  return true;
}
bool Ws::SendIPCMessageToFrame(bool internal,
                                        bool send_to_all,
                                        int32_t frame_id,
                                        const std::string& channel,
                                        v8::Local<v8::Value> args) {
  blink::CloneableMessage message;
  if (!gin::ConvertFromV8(isolate(), args, &message)) {
    isolate()->ThrowException(v8::Exception::Error(
        gin::StringToV8(isolate(), "Failed to serialize arguments")));
    return false;
  }
  auto frames = ontents()->GetAllFrames();
  auto iter = std::find_if(frames.begin(), frames.end(), [frame_id](auto* f) {
    return f->GetRoutingID() == frame_id;
  });
  if (iter == frames.end())
    return false;
  if (!(*iter)->IsRenderFrameLive())
    return false;
  mojo::AssociatedRemote<mojom::ElectronRenderer> electron_renderer;
  (*iter)->GetRemoteAssociatedInterfaces()->GetInterface(&electron_renderer);
  electron_renderer->Message(internal, send_to_all, channel, std::move(message),
                             0 /* sender_id */);
  return true;