我们正在尝试使用以下链接https://dart.dev/null-safety/migration-guide将flutter项目升级到null安全迁移。
dart pub outdated --mode=null-safety - Successful dart pub get - Successful手动迁移代码-https://dart.dev/null-safety/migration-guide#migrating-by-hand- Successful dart migrate - Successful
尝试运行Flutter命令时，以下代码中出现错误（Flutter运行）

static Future<AppStrings> getAppText(String local) async {
    var appTextBox = await Hive.openBox("appTextBox");
    AppStrings appText = new AppStrings(
      mainPageTitle: appTextBox.get('mainPageTitle'),
      timeText: appTextBox.get('timeText'),
      minutesText: appTextBox.get('minutesText'),
      mainPageSubtitle: appTextBox.get('mainPageSubtitle'),
      mainPageParagraph: appTextBox.get('mainPageParagraph'),
      mainPageButton: appTextBox.get('mainPageButton'),
      restartButton: appTextBox.get('restartButton'),
      backButton: appTextBox.get('backButton'),
      profileTitle: appTextBox.get('profileTitle'),
      loadingPageSubtitle: appTextBox.get('loadingPageSubtitle'),
      loadingPageBottomText: appTextBox.get('loadingPageBottomText'),
      loadingPageTitle: appTextBox.get('loadingPageTitle'),
      profileButton: appTextBox.get('profileButton'),
      resultRestart: appTextBox.get('resultRestart'),
      resultTitle: appTextBox.get('resultTitle'),
      resultSwipe: appTextBox.get('resultSwipe'),
      secondaryTitle: appTextBox.get('secondaryTitle'),
      tretiaryProductTitle: appTextBox.get('tertiaryTitle'),
    );
    return appText;
  }

更新：-
这就是我们如何从main.dart文件调用这个方法

AppStrings? appText = (await DatabaseUtils.getAppText(local ?? ''));
  return Data(
      allProfiles: allProfiles,...........
)