Mengikuti tutorial "sekolah koding flutter - 6 merapikan class sendiri "

import 'dart:math';

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Selamat Datang',
      home: RandomWord(),
    );
  }
}

class RandomWord extends StatefulWidget {
  @override
  _RandomWordState createState() => _RandomWordState();
}

class _RandomWordState extends State<RandomWord> {
  var savedWords = [];
  String randomWord = WordPair.random().asString;

  void _changeWord() {
    setState(() {
      randomWord = WordPair.random().asString;
    });
  }

  void _saveWords() {
    savedWords.add(randomWord);
    Navigator.push(
        context,
        MaterialPageRoute(
            builder: (context) => SavedWordScreen(savedWords: savedWords)));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text('Aplikasi Flutter ke 2')),
        body: Center(
            child:
                Column(mainAxisAlignment: MainAxisAlignment.center, children: [
          Text(randomWord, style: TextStyle(fontSize: 40)),
          IconButton(icon: Icon(Icons.favorite_border), onPressed: _saveWords)
        ])),
        floatingActionButton: FloatingActionButton(
            onPressed: _changeWord, child: Icon(Icons.play_arrow)));
  }
}

class SavedWordScreen extends StatelessWidget {
  var savedWords = [];

  SavedWordScreen({this.savedWords}); //error disini

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text('Saved Word'),
        ),
        body: Center(
            child:
                Text(savedWords.join(" - "), style: TextStyle(fontSize: 40))));
  }
}

Saya buat seperti ini tapi masih terdapat error apakah yang saya buat ada yang salah. Sudah coba untuk mancari masalah nya tapi masih belum ketemu.

Mohon bantuannya para master dan suhu.