CustomScrollView within ExpansionTile error - flutter

Question

Tried to fix this reading some documentation and some open issues but was not lucky.. Could someone please help?
I am getting this error:
type 'bool' is not a subtype of type 'double' in type cast
Not sure why though I tried adding container wrapping the component, adding height, adding flexible box etc...
No lucky
`import 'package:flutter/material.dart';
class SampleData {
SampleData(this.title, [this.children = const <SizedBox>[]]);
final String title;
final List<SizedBox> children;
}
final List<SampleData> data = <SampleData>[
SampleData("IT", [
SizedBox(
height: 300,
width: 300,
child: CustomScrollView(
scrollDirection: Axis.horizontal,
slivers: <Widget>[
new SliverToBoxAdapter(
child: Text('fesfefes'),
),
],
),
),
]),
];
class Branch extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Test 123'),
),
body: Container(
width: 500,
child: ListView.builder(
scrollDirection: Axis.horizontal,
itemBuilder: (BuildContext context, int index) => Item(data[index]),
itemCount: data.length,
),
),
);
}
}
// Displays one Entry. If the entry has children then it's displayed
// with an ExpansionTile.
class Item extends StatelessWidget {
const Item(this.sample);
final SampleData sample;
Widget _buildTiles(SampleData root) {
return SizedBox(
width: 500,
child: ExpansionTile(
key: PageStorageKey<SampleData>(root),
title: Text(root.title),
children: root.children,
),
);
}
#override
Widget build(BuildContext context) {
return _buildTiles(sample);
}
}
`

Answer 1

You can copy paste run full code blow
You can remove
//key: PageStorageKey<SampleData>(root),
working demo
full code
import 'package:flutter/material.dart';
class SampleData {
SampleData(this.title, [this.children = const <SizedBox>[]]);
final String title;
final List<SizedBox> children;
}
final List<SampleData> data = <SampleData>[
SampleData("IT", [
SizedBox(
height: 300,
width: 300,
child: CustomScrollView(
scrollDirection: Axis.horizontal,
slivers: <Widget>[
new SliverToBoxAdapter(
child: Text('fesfefes'),
),
],
),
),
]),
];
class Branch extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Test 123'),
),
body: Container(
width: 500,
child: ListView.builder(
scrollDirection: Axis.horizontal,
itemBuilder: (BuildContext context, int index) => Item(data[index]),
itemCount: data.length,
),
),
);
}
}
// Displays one Entry. If the entry has children then it's displayed
// with an ExpansionTile.
class Item extends StatelessWidget {
const Item(this.sample);
final SampleData sample;
Widget _buildTiles(SampleData root) {
return SizedBox(
width: 500,
child: ExpansionTile(
//key: PageStorageKey<SampleData>(root),
title: Text(root.title),
children: root.children,
),
);
}
#override
Widget build(BuildContext context) {
return _buildTiles(sample);
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: Branch(),
);
}
}