Flutter Failed assertion: line 1214 pos 12: 'renderObject.child == child': is not true

I recently worked on a project but now I've moved to other project and I've removed all boiler plate code from main.dart and add my own HomePage code. code is here:

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Text("Hello"),
    );
  }
}

But when I RUN this code this throw this error which I've given on the title bar. Any Solution for this Thanks in Advance <3.