Как решить «The superclass 'PreferredSize' doesn't have a zero argument constructor.» при миграции на Flutter 2?

Question

[Валентин]

Перевёл проект на свежую версию Флаттера и получил вот такую ошибку:

The superclass 'PreferredSize' doesn't have a zero argument constructor.
Try declaring a zero argument constructor in 'PreferredSize', or explicitly invoking a different constructor in 'PreferredSize'.

Гугл предложил такое решение, но оно не сработало:

You may not even have to extend PreferredSize you may just wrap an appBar or any other widget inside a PreferredSize and just specify its height.

PreferredSize(
preferredSize: Size.fromHeight(72),
child: AppBar(
title: Text(title, style: TextStyles.h1),
centerTitle: false,
elevation: 0,
brightness: Brightness.light,
backwardsCompatibility: false,
bottom: bottomAppBarWidget,
))

Вот код файла с ошибкой:

import 'package:flutter/material.dart';
import 'package:flutter_svg/flutter_svg.dart';

import '../../../size_config.dart';

class CustomAppBar extends PreferredSize {
  double? rating;

  CustomAppBar({@required this.rating});

  @override
  Size get preferredSize => Size.fromHeight(AppBar().preferredSize.height);

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: Padding(
        padding:
            EdgeInsets.symmetric(horizontal: getProportionateScreenWidth(20)),
        child: Row(
          children: [
            SizedBox(
              height: getProportionateScreenWidth(40),
              width: getProportionateScreenWidth(40),
              child: FlatButton(
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(60),
                ),
                color: Colors.white,
                padding: EdgeInsets.zero,
                onPressed: () => Navigator.pop(context),
                child: SvgPicture.asset(
                  "assets/icons/Back ICon.svg",
                  height: 15,
                ),
              ),
            ),
            Spacer(),
            Container(
              padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 5),
              decoration: BoxDecoration(
                color: Colors.white,
                borderRadius: BorderRadius.circular(14),
              ),
              child: Row(
                children: [
                  Text(
                    "$rating",
                    style: const TextStyle(
                      fontSize: 14,
                      fontWeight: FontWeight.w600,
                    ),
                  ),
                  const SizedBox(width: 5),
                  SvgPicture.asset("assets/icons/Star Icon.svg"),
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}