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
SecurityStateTabHelper::CreateForWs(ontents());
  InitZoomController(ontents(), options);
#if BUILDFLAG(ENABLE_ELECTRON_EXTENSIONS)
  extensions::ElectronExtensionWsObserver::CreateForWs(
      ontents());
  script_executor_.reset(new extensions::ScriptExecutor(ontents()));
#endif
  registry_.AddInterface(base::BindRepeating(&Ws::BindElectronBrowser,
                                             base::Unretained(this)));
  bindings_.set_connection_error_handler(base::BindRepeating(
      &Ws::OnElectronBrowserConnectionError, base::Unretained(this)));
  AutofillDriverFactory::CreateForWs(ontents());
  ontents()->SetUserAgentOverride(GetBrowserContext()->GetUserAgent(),
                                       false);
  if (IsGuest()) {
    NativeWindow* owner_window = nullptr;
    if (embedder_) {
      
      auto* relay =
          NativeWindowRelay::FromWs(embedder_->ontents());
      if (relay)
        owner_window = relay->GetNativeWindow();
    }
    if (owner_window)
      SetOwnerWindow(owner_window);
  }
  Init(isolate);
  AttachAsUserData(ontents());
}
Ws::~Ws() {