I am getting the following error when I try to run the url using Webview on Flutter web:

WebViewPlatform.instance != null
“A platform implementation for webview_flutter has not been set. Please ensure that an
implementation of WebViewPlatform has been set to WebViewPlatform.instance before use. For unit
testing, WebViewPlatform.instance can be set with your own test implementation.”

Here is the code snippet:

class CheckoutPage extends StatefulWidget {
  const CheckoutPage({super.key, required this.url});
  final String url;

  @override
  State<CheckoutPage> createState() => _CheckoutPageState();
}

class _CheckoutPageState extends State<CheckoutPage> {
  WebViewController controller = WebViewController()
    ..setJavaScriptMode(JavaScriptMode.unrestricted);

  @override
  Widget build(BuildContext context) {
    controller.loadRequest(Uri.parse(widget.url));
    return Scaffold(body: WebViewWidget(controller: controller));
  }
}

I am running on Flutter web and what is the fix?