Problem when testing custom webview widget

// Automatic FlutterFlow imports
import '/backend/backend.dart';
import '/flutter_flow/flutter_flow_theme.dart';
import '/flutter_flow/flutter_flow_util.dart';
import '/custom_code/widgets/index.dart'; // Imports other custom widgets
import '/flutter_flow/custom_functions.dart'; // Imports custom functions
import 'package:flutter/material.dart';
// Begin custom widget code
// DO NOT REMOVE OR MODIFY THE CODE ABOVE!

import 'package:webview_flutter/webview_flutter.dart';
import 'package:webview_flutter_wkwebview/webview_flutter_wkwebview.dart';

class InteractiveWebView extends StatefulWidget {
  const InteractiveWebView({
    super.key,
    this.width,
    this.height,
    required this.threadId,
  });

  final double? width;
  final double? height;
  final String threadId;

  @override
  State<InteractiveWebView> createState() => _InteractiveWebViewState();
}

class _InteractiveWebViewState extends State<InteractiveWebView> {
  late final WebViewController _controller;

  @override
  void initState() {
    super.initState();

    final PlatformWebViewControllerCreationParams params =
        const PlatformWebViewControllerCreationParams();

    _controller = WebViewController.fromPlatformCreationParams(params)
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..addJavaScriptChannel(
        'JSChannel',
        onMessageReceived: (JavaScriptMessage message) {
          _showSnackbar(message.message);
        },
      )
      ..loadRequest(
        Uri.parse(
            'https://babble-a09e7.web.app/testwebview.html/${widget.threadId}'),
      );
  }

  void _showSnackbar(String text) {
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text('Message from Web: $text')),
    );
  }

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: widget.width ?? double.infinity,
      height: widget.height ?? 500,
      child: WebViewWidget(controller: _controller),
    );
  }
}