Flutter How Can I Show Dialog on Another Page - flutter

Question

I want to show dialog when I press the button I want to be navigated to another page and then I want to show a dialog indicating that I have been navigated to that page.
So I try this code;
InkWell(
onTap: () async {
Navigator.pushAndRemoveUntil(
context,
MaterialPageRoute(
builder: (context) => BottomBarD()),
(route) => false);
Dialog(
child: Container(
child: Column(
children: [
Text(
"Navigated to Another Page",
style: TextStyle(
fontFamily: "Quando",
fontWeight: FontWeight.w500,
fontSize: 15,
),
),
TextButton(
onPressed: () async {
Navigator.of(context).pop();
},
child: Text(
"Okey",
style: TextStyle(
fontFamily: "Quando",
fontSize: 15,
),
),
),
],
),
),
);
},
child: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [Colors.orangeAccent, Colors.red],
begin: Alignment.bottomRight,
end: Alignment.centerLeft),
borderRadius: BorderRadius.only(
bottomLeft: Radius.circular(112.0),
topLeft: Radius.circular(112.0),
bottomRight: Radius.circular(112.0),
topRight: Radius.circular(112.0),
),
),
height: MediaQuery.of(context).size.height * 0.065,
width: MediaQuery.of(context).size.width * 0.80,
margin: EdgeInsets.only(
top: 30.0,
bottom: 10.0,
),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
child: Text(
"Navigate and ShowDialog Button",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.white,
fontSize: 17,
fontFamily: "Quando"),
),
),
],
),
),
),
But when I press the okay button in the dialog, the okay button does not work and it gives a that error;
Unhandled Exception: Null check operator used on a null value

Answer 1

This worked fine on DartPad:
void _incrementCounter() {
Navigator.of(context).push(MaterialPageRoute(
builder: (c) => Scaffold(body: Text('new page'))
));
showDialog(context: context,
builder: (c) => AlertDialog(content: Text('the dialog in it'),)
);
}
Notice that .push() returns a Future immediately. The dialog you show after that is shown on top of page 2, since we don't await for it.

Answer 2

I put the Dialog in my second page BottomBarD() and I displayed it based on a conditional field every time the BottomBarD() loads.