Navigation Issue in my flutter Application. Unable to redirect to the required page or screen in flutter

Question

Below code mainform.dart when run individually i.e keeping Dart entrypint: as mainform.dart working fine and redirecting or navigating to the correct page i.e Feed();

mainform.dart

import 'package:sqlite_crud_flutter/detail.dart';
import 'package:sqlite_crud_flutter/login.dart';
import 'package:sqlite_crud_flutter/notifier/food_notifier.dart';
import 'package:sqlite_crud_flutter/feed.dart';

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import 'notifier/auth_notifier.dart';


void main() => runApp(MultiProvider(
      providers: [
        ChangeNotifierProvider(
          create: (context) => AuthNotifier(),
        ),
        ChangeNotifierProvider(
          create: (context) => FoodNotifier(),
        ),
      ],
      child: MainFormPage(),
    ));

class MainFormPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Application Name',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        accentColor: Colors.lightBlue,
      ),
      home: Consumer<AuthNotifier>(
        builder: (context, notifier, child) {
          return  Feed();
        },
      ),
    );
  }
}

But where as when I want to redirect to the Feed() page from another screen or page of my main application using

 onTap: () {

Navigator.push(context, MaterialPageRoute(builder: (context) =>
MainFormPage()

)
);

},

I am seeing a blank screen with error

Another exception was thrown: Instance of 'DiagnosticsProperty<void>'"

How to the Feed page from another screen?

Screenshot of the error shown on mobile when debugged: