I am trying to create a program to display the time. When I try to display the time using a Text widget flutter throws an exception “Expected a value of type ‘String’, but got one of type ‘Null'”
I have the following dart files-:
1. main.dart

// ignore_for_file: prefer_const_constructors

import 'package:flutter/material.dart';
import 'package:flutter_worldtime/pages/chose_location.dart';
import 'package:flutter_worldtime/pages/home.dart';
import 'package:flutter_worldtime/pages/loading.dart';

void main() => runApp(MaterialApp(
  initialRoute: '/',
  routes: {
    '/': (context) => Loading(),
    '/home': (context) => Home(),
    '/location': (context) => chooseLocation()
  },
));

2.home.dart

// ignore_for_file: prefer_const_constructors

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

class Home extends StatefulWidget {
  const Home({super.key});

  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {

  Map data = {};

  @override
  Widget build(BuildContext context) {

    Map? data = ModalRoute.of(context)?.settings.arguments as Map?;
      if (kDebugMode) {
        print(data);
      }

    return Scaffold(
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.fromLTRB(0,120.0,0,0),
          child: Column(
            children: <Widget>[
              TextButton.icon(
                onPressed: (){
                  Navigator.pushNamed(context, '/location');
                }, 
                icon: Icon(Icons.edit_location),
                label: Text('edit location'),
              ),
              SizedBox(height: 20.0,),
              Row(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  Text(
                    data?['location'],
                    style: TextStyle(
                      fontSize: 28.0,
                      letterSpacing: 2.0,
                    ),
                  )
                ],
              ),
              SizedBox(height: 20.0,),
              Text(
                data?['time'],
                style: TextStyle(
                  fontSize: 66.0
                ),
              )
            ],
          ),
        )      )
    );
  }
}

3.loading.dart

import 'package:flutter/material.dart';
import 'package:flutter_worldtime/services/world_time.dart';
import 'package:flutter_spinkit/flutter_spinkit.dart';

class Loading extends StatefulWidget {
  const Loading({super.key});

  @override
  State<Loading> createState() => _LoadingState();
}

class _LoadingState extends State<Loading> {

  void setupWorldTime() async {
    WorldTime instance = WorldTime(location: 'Berlin', flag: 'germany.png', url: 'Europe/Berlin');
    await instance.getTime();
    //print(instance.time);
    // ignore: use_build_context_synchronously
    Navigator.pushReplacementNamed(context, '/home', arguments: {
      'location': instance.location, 'flag': instance.flag, 'time': instance.time
    });
  }

  @override
  void initState() {
    super.initState();
    setupWorldTime();
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(
        child: SpinKitFadingCircle(
          color: Colors.white,
          size: 50.0,
      ),
    )
   );
  }
}

4.world_time.dart

import 'package:flutter/foundation.dart';
import 'package:http/http.dart';
import 'dart:convert';
import 'package:intl/intl.dart';

class WorldTime {
  String location; //location name for the UI
  String time=''; //time in that location
  String flag; //url to an asset flag icon
  String url; //location url for API endpoint

  WorldTime({ required this.location, required this.flag, required this.url});

  Future<void> getTime() async {

    try{
      //make the request
      Response response = await get(Uri.parse('https://worldtimeapi.org/api/timezone/$url'));
      Map data = jsonDecode(response.body);
      //print(data);

      //get properties from data
      String datetime = data['datetime'];
      String offsetHour = data['utc_offset'].substring(1,3);
      String offsetMinutes = data['utc_offset'].substring(4,6);
      //print(datetime);
      //print(offset_hour);
      //print(offset_minutes);

      //create a datetime object
      DateTime now = DateTime.parse(datetime);
      now = now.add(Duration(hours: int.parse(offsetHour),minutes: int.parse(offsetMinutes)));
      //print(now);
      time = DateFormat.jm().format(now); //set the time property
    }
    catch (e) {
      if (kDebugMode) {
        print('caught error: $e');
      }
      time = 'could not get time data';
    }

    
  }
}

I was trying to display the time and location of the place. I used the Navigator to change to the home screen from loading screen, and then used ModalRoute to take the arguments.
The exception is thrown on the two Text widgets in the home.dart file. it is displayed on the loading screen, but then is replaced by the home.dart screen which still displays the TextButton and Text widgets as expected.
this is the full error that is displayed on the debug console-
The following TypeErrorImpl was thrown building Home(dirty, dependencies: [_ModalScopeStatus],
state: _HomeState#96849):
Expected a value of type ‘String’, but got one of type ‘Null’