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
bool send_to_all,
                            int32_t ontents_id,
                            const std::string& channel,
                            blink::CloneableMessage arguments) {
  TRACE_EVENT1("electron", "Ws::MessageTo", "channel", channel);
  auto* ontents = gin_helper::TrackableObject<Ws>::FromWeakMapID(
      isolate(), ontents_id);
  if (ontents) {
    ontents->SendIPCMessageWithSender(internal, send_to_all, channel,
                                           std::move(arguments), ID());
  }
}
void Ws::MessageHost(const std::string& channel,
                              blink::CloneableMessage arguments) {
  TRACE_EVENT1("electron", "Ws::MessageHost", "channel", channel);
  // ws.emit('ipc-message-host', new Event(), channel, args);
  EmitWithSender("ipc-message-host", bindings_.dispatch_context(),
                 InvokeCallback(), channel, std::move(arguments));
}
#if BUILDFLAG(ENABLE_REMOTE_MODULE)
void Ws::DereferenceRemoteJSObject(const std::string& context_id,