Unhandled Exception: NoSuchMethodError: The getter 'body' was called on null – Flutter

I’m trying to fetch data from an api by passing bearer token but it is throwing this exception. Here’s my code below :

This is my afterLoginResponse.dart class –

 class AfterLoginResponse {
    LoginData? data;
    bool? operator;
    bool? success;

 AfterLoginResponse({
   required this.operator,
   required this.success,
   required this.data,
});

AfterLoginResponse.fromJson(Map<String, dynamic> json) {
   operator = json['operator'];
  success = json['success'];
  data = LoginData.fromJson(json["data"]);
}

Map<String, dynamic> toJson() => {
  "operator": operator,
  "success": success,
  "data": data!.toJson(),
 };
}

Below is my loginData.dart class ->

class LoginData {
  String? name;
 String? ext;
 String? dName;
 String? password;

LoginData({
  required this.name,
  required this.ext,
  required this.dName,
  required this.password,
});

factory LoginData.fromJson(Map<String, dynamic> json) {
 return LoginData(
    name: json['name'],
    ext: json['ext'],
    dName: json['d_Name'],
    password : json['password'],
   );
}

Map<String, dynamic> toJson() {
  final Map<String, dynamic> data = <String, dynamic>{};
  data['name'] = name;
  data['ext'] = ext;
  data['d_Name'] = dName;
  data['password'] = password;
  return data;
 }
}

This is my apiService.dart class –

class ApiService{
 String? token;
 var response1;
 var response2;

Future<LoginResponseData> loginApiCall(Map<String, dynamic> param) async{
  var url = Uri.parse(ApiUrls.login_url);
  response1 =  await http.post(url, body: param);
  final data = jsonDecode(response1.body);
  token = LoginResponseData.fromJson(json.decode(response1.body)).token;
    return LoginResponseData(user: data['user'], token: 
        data['token'],error:data['error']);
  }

Future<AfterLoginResponse> postLoginApiCall() async{
  var afterLoginUrl = Uri.parse(ApiUrls.postLogin_url);
  response2 = await http.get(afterLoginUrl , headers: {
    'Content-Type': 'application/json',
    'Accept': 'application/json',
    'Authorization': 'Bearer 
  ${LoginResponseData.fromJson(json.decode(response1.body)).token}'
 });

  if(response2.statusCode == 200){
    var data =  jsonDecode(response2.body);
    return AfterLoginResponse.fromJson(data);
   }else{
   throw Exception('Failed to load data');
  }
 }
}

Here is my UI –

 class HomePage extends StatefulWidget {
   String email, password;

 HomePage({Key? key, required this.email, required this.password})
     : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
  }

class _HomePageState extends State<HomePage> {

  late Future<AfterLoginResponse> afterLoginResponse;

  final apiService = ApiService();

  callPostLoginApi(){
    return FutureBuilder<AfterLoginResponse>(
     future: afterLoginResponse,
     builder: (context, snapshot) {
       if (snapshot.hasData) {
         return Text(snapshot.data!);
         print(snapshot.data);
      } else if (snapshot.hasError) {
        return Text('${snapshot.error}');
      }

      // By default, show a loading spinner.
      return const CircularProgressIndicator();
     },
   );
  }


 @override
 Widget build(BuildContext context) {
  return Scaffold(
     appBar: AppBar(
       title: const Text('Home page'),
       centerTitle: true,
     ),
     body: Center(
       child: Column(
         children: [
           ElevatedButton(
             onPressed: callPostLoginApi,
               child: const Text('Click me'))
          ],
        ),
      )
   );
 }

The above code is throwing following exception –
Unhandled Exception: NoSuchMethodError: The getter ‘body’ was called on null.
Receiver: null
E/flutter (28599): Tried calling: body
E/flutter (28599): #0 Object.noSuchMethod (dart:core-patch/object_patch.dart:38:5)
.
.
.