Expanded widgets must be placed inside Flex widgets : <p>New to flutter, can some one tells me whats wrong with below code<a href="https://i.stack.imgur.com/5b5lp.png" rel="noreferrer"><img src="https://i.stack.imgur.com/5b5lp.png" alt="enter image description here"></a></p>

<pre><code>  class GamePage extends StatelessWidget {
  int _row;
  int _column;

  GamePage(this._row,this._column);

  @override
  Widget build(BuildContext context) {
    return new Material(
      color: Colors.deepPurpleAccent,
      child:new Expanded(
          child:new GridView.count(crossAxisCount: _column,children: new List.generate(_row*_column, (index) {
        return new Center(
            child: new CellWidget()
        );
      }),) )


    );
  }
}
</code></pre>

<p>Attaching error screenshot.</p>
