小编Kai*_*ins的帖子

我是 flutter 和 dart 的新手，我正在尝试克隆 Instagram 以用于学习目的，但我收到以下错误。

你能帮我找出代码哪里不正确吗？

最后输出消息错误。

我尝试谷歌，并重构代码以应用空安全，但实际上我不知道错误的代码到底在哪里。

主程序.dart

import 'package:flutter/material.dart';
import 'package:instagram_flutter/responsive/mobile_screen_layout.dart';
import 'package:instagram_flutter/responsive/responsive_layout_screen.dart';
import 'package:instagram_flutter/responsive/web_screen_layout.dart';
import 'package:instagram_flutter/utils/colors.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Instagram Clone',
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: mobileBackgroundColor,
      ),
      home: ResponsiveLayout(
        webScreenLayout: WebScreenLayout(),
        mobileScreenLayout: MobileScreenLayout(),
      ),
    );
  }
}

mobile_screen_layout.dart

import 'package:flutter/material.dart';

class MobileScreenLayout extends StatelessWidget {
  const MobileScreenLayout({super.key}); …