Estou com este erro na criação do projeto byteBank do curso de flutter perssistencia em BD

Segue o código completo:

import 'package:bytebank/screens/contact_form.dart';
import 'package:flutter/material.dart';

import '../models/contact.dart';

class ContactsList extends StatelessWidget {
  const ContactsList({Key? key}) : super(key: key);

  final List<Contact> contacts = List();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Contatos'),
      ),
      body: ListView.builder(
        itemBuilder: (context, index){
          final Contact contact = contacts[index];
          return _ContactItem(contact);
        },
        itemCount: contacts.length,
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.of(context).push(
            MaterialPageRoute(
              builder: (context) => ContactForm(),
            ),
          ).then((newContact) => debugPrint(newContact.toString()));
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

class _ContactItem extends StatelessWidget {

  final Contact contact;

  _ContactItem(this.contact);

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        title: Text(
          contact.nome,
          style: TextStyle(fontSize: 24.0),
        ),
        subtitle: Text(
          contact.numeroConta,
          style: TextStyle(fontSize: 16.0),
        ),
      ),
    );
  }

}