flutter show alert dialog in dart class without context code example

Example: flutter display alert dialog after server error

Provider.of<NewsProvider>(context, listen: false)
.fetchAndSetNewsList()
.catchError((error) => showDialog(context: context, builder: (context) {
   return new SimpleDialog(
       children: <Widget>[
            new Center(child: new Container(child: new Text('foo')))
       ]);
}))