How to use pushReplacment method using go-router package?

How can we use pushReplacment using go-router package

I tried this but didn't work

context.pushReplacement("register"); 

To use the Navigator API with named routes (pushNamed, pushReplacementNamed, or pushNamedAndRemoveUntil), the Navigator must be provided with an onGenerateRoute handler.

Here is my setup

final GoRouter _router = GoRouter(
    debugLogDiagnostics: true,

  routes: <RouteBase>[
    GoRoute(
      path: '/',
      builder: (BuildContext context, GoRouterState state) {
        return const MainPage();
      },
      routes: <RouteBase>[
        GoRoute(
          path: 'login',
          builder: (BuildContext context, GoRouterState state) {
            return const Login();
          },
        ),
        GoRoute(
          path: 'register',
          builder: (BuildContext context, GoRouterState state) {
            return const SignUp();
          },
        ),
        
      ],
    ),
  ],
);

I want to navigate between routes in flutter.

Navigate and Replace: Use the go method of GoRouter to navigate to the new route while ensuring the current route is replaced. Example:

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  MyApp({Key? key}) : super(key: key);

  final GoRouter _router = GoRouter(
    routes: [
      GoRoute(
        path: '/',
        builder: (BuildContext context, GoRouterState state) => HomeScreen(),
      ),
      GoRoute(
        path: '/details',
        builder: (BuildContext context, GoRouterState state) => DetailsScreen(),
      ),
    ],
  );

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routerConfig: _router,
      title: 'GoRouter Example',
    );
  }
}

class HomeScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Home')),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            // This replaces the current route with the details route
            context.go('/details');
          },
          child: Text('Go to Details'),
        ),
      ),
    );
  }
}

class DetailsScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Details')),
      body: Center(
        child: Text('Welcome to the Details Screen!'),
      ),
    );
  }
}

In this example, when you press the button on the HomeScreen, it navigates to the DetailsScreen using context.go('/details'). This effectively replaces the current route in the navigation stack.