The relevant error-causing widget was
import 'package:flutter/material.dart';
void main() => runApp(App());
class App extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(),
body: Center(
child: Container(
margin: EdgeInsets.all(32),
decoration: BoxDecoration(border: Border.all(color: Colors.red)),
child: ListView(
shrinkWrap: true,
children: <Widget>[
ListTile(title: Text('Item 1')),
ListTile(title: Text('Item 2')),
ListTile(title: Text('Item 3')),
],
),
),
),
),
);
}
}