LateInitializationError:字段尚未初始化。在FutureBuilder中运行firebase查询后，.then()命令未运行

late String result; // 声明一个非空字段

Future<String> fetchData() async {
  // 执行Firebase查询操作，返回一个Future对象
  // 假设这里是你的Firebase查询代码
  await Future.delayed(Duration(seconds: 2)); // 模拟异步操作
  return '查询结果';
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: FutureBuilder<String>(
          future: fetchData(), // 执行Firebase查询
          builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
            if (snapshot.connectionState == ConnectionState.waiting) {
              return CircularProgressIndicator();
            } else if (snapshot.hasError) {
              return Text('发生错误: ${snapshot.error}');
            } else {
              result = snapshot.data!; // 将查询结果赋值给非空字段
              return Text('查询结果: $result');
            }
          },
        ),
      ),
    );
  }
}