我正面临颤振 webview 问题

Question

我是新手。我在 flutter_webview 中遇到了一个问题，这里是我的代码 IDK，它有什么问题。我在 StackOverflow 和官方插件的帮助下编写了这段代码。我的 HTML 文件工作正常

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
class Licences extends StatefulWidget {
@override
_LicencesState createState() => _LicencesState();
}
class _LicencesState extends State<Licences> {
  WebViewController webViewController;
  String filePath = 'files/PrivacyPolicy.html';
 loadHtml() async {
   String data = await rootBundle.loadString(filePath);
   webViewController.loadUrl(Uri.dataFromString(data,
           mimeType: 'text/html', encoding: Encoding.getByName('utf-8'))
        .toString());
 }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
     appBar: AppBar(
       title: const Text('Open-Source Licences'),
      ),
       body: Builder(builder: (BuildContext context) {
        return WebView(
          initialUrl: '',
          javascriptMode: JavascriptMode.unrestricted,
           onWebViewCreated: (WebViewController controller) {
             webViewController = controller;
            loadHtml();
           },
         );
      }),
    );
   }
 }