Error saat klik tombol + di home screen

Malam coach, saya ada problem saat klik button +,
muncul error sebagai berikut.

Bad state: No element
See also: https://flutter.dev/
docs/testing/errors

berikut code home_screen

import ‘package:flutter/material.dart’;
import ‘package:flutter_state/models/note.dart’;
import ‘package:flutter_state/screens/add_or_detail_screen.dart’;
import ‘package:flutter_state/widgets/notes_grid.dart’;

class HomeScreen extends StatefulWidget {
//const HomeScreen({Key key}) : super(key: key);

@override
State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(‘Notes’),
),
body: NotesGrid(),
floatingActionButton: FloatingActionButton(
onPressed: () {
Navigator.of(context).pushNamed(AddOrDetailScreen.routeName);
},
child: Icon(Icons.add),
),
);
}
}

dan code add_or_detail_screen

import ‘package:flutter/material.dart’;
import ‘package:flutter_state/models/note.dart’;
import ‘package:flutter_state/providers/notes.dart’;
import ‘package:intl/intl.dart’;
import ‘package:provider/provider.dart’;

class AddOrDetailScreen extends StatefulWidget {
static const routeName = ‘/addOrDetailScreen’;
@override
State<AddOrDetailScreen> createState() => _AddOrDetailScreenState();
}

class _AddOrDetailScreenState extends State<AddOrDetailScreen> {
Note _note = Note(
id: null,
title: ”,
note: ”,
updatedAt: null,
createdAt: null,
);

bool init = true;

final _formKey = GlobalKey<FormState>();

void submitNote() {
_formKey.currentState.save();
final now = DateTime.now();
_note = _note.copyWith(updatedAt: now, createdAt: now);
final notesProvider = Provider.of<Notes>(context, listen: false);
if (_note.id == null) {
notesProvider.addNote(_note);
} else {
notesProvider.updateNote(_note);
}
Navigator.of(context).pop();
}

@override
void didChangeDependencies() {
if (init) {
String id = ModalRoute.of(context).settings.arguments as String;
_note = Provider.of<Notes>(context).getNote(id);
init = false;
}
super.didChangeDependencies();
}

String _convertDate(DateTime dateTime) {
int diff = DateTime.now().difference(dateTime).inDays;
if (diff > 0) return DateFormat(‘dd-MM-yyyy’).format(dateTime);

return DateFormat(‘hh:mm’).format(dateTime);
}

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: [
TextButton(
onPressed: submitNote,
child: Text(‘Simpan’),
)
],
),
body: Stack(
children: [
Container(
height: double.infinity,
padding: EdgeInsets.all(12),
child: SingleChildScrollView(
child: Form(
key: _formKey,
child: Column(
children: [
TextFormField(
initialValue: _note.title,
decoration: InputDecoration(
hintText: ‘Judul’,
border: InputBorder.none,
),
onSaved: (value) {
_note = _note.copyWith(title: value);
},
),
TextFormField(
initialValue: _note.note,
decoration: InputDecoration(
hintText: ‘Tulis Catatan Disini…’,
border: InputBorder.none),
onSaved: (value) {
_note = _note.copyWith(note: value);
},
maxLines: null,
),
],
),
),
),
),
Positioned(
bottom: 10,
right: 10,
child: Text(‘Terakhir Diubah ${_convertDate(_note.updatedAt)}’)),
],
),
);
}
}