I am getting response data from an api while passing in a response body. I have built my state, event, repository of my request but upon calling the user details event in my home page where I want to access my data, I am getting an error below

W/WindowOnBackDispatcher(10169): OnBackInvokedCallback is not enabled for the application.
W/WindowOnBackDispatcher(10169): Set ‘android:enableOnBackInvokedCallback=”true”‘ in the application manifest.
E/flutter (10169): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: Bad state: add(FetchUserDetails) was called without a registered event handler.
E/flutter (10169): Make sure to register a handler via on((event, emit) {…})
E/flutter (10169): #0 Bloc.add. (package:bloc/src/bloc.dart:91:9)
E/flutter (10169): #1 Bloc.add (package:bloc/src/bloc.dart:97:6)
E/flutter (10169): #2 _DashboardPageState._loadUsernameAndPin (package:mobile_banking/views/dashboard_page.dart:108:39)
E/flutter (10169):

Here is how I am implementing my whole logic.

    class UserDetails {
  final String username;
  final String password;
  final String deviceId; // Add required fields
  final String ipAddress;
  final String appVersion;
  final String platform;

  UserDetails({
    required this.username,
    required this.password,
    required this.deviceId,
    required this.ipAddress,
    required this.appVersion,
    required this.platform,
  });

  factory UserDetails.fromJson(Map<String, dynamic> json) {
    final data = json['data'];
    print(data);
    return UserDetails(
      username: json['username'] ?? '',
      password: json['password'] ?? '',
      deviceId: json['deviceId'] ?? '',
      ipAddress: json['ipAddress'] ?? '',
      appVersion: json['appVersion'] ?? '',
      platform: json['platform'] ?? '',
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'username': username,
      'password': password,
      'deviceId': deviceId,
      'ipAddress': ipAddress,
      'appVersion': appVersion,
      'platform': platform,
    };
  }

  @override
  String toString() {
    return 'UserDetails{username: $username, deviceId: $deviceId, ipAddress: $ipAddress, appVersion: $appVersion, platform: $platform}';
  }
}

my user details repository

class UserDetailsRepository {
  final String endpoint = 'url';

  late HttpService httpService;

  Future<UserDetails> getUserDetails(UserDetails userDetails) async {
    try {
      print('Requesting user details with: ${userDetails.toJson()}');
      final response = await httpService.request(
        method: HttpMethod.post,
        url: '$endpoint/api/iBank/UserAuth',
        body: userDetails.toJson(),
      );
      print("Response body: $response");
      print("Return response body: ${UserDetails.fromJson(response)}");
      return UserDetails.fromJson(response);
    } catch (e) {
      throw Exception('Failed to get user details');
    }
  }
}

my state

abstract class UserDetailsState extends Equatable {
  @override
  List<Object?> get props => [];
}

class UserDetailsInitial extends UserDetailsState {}

class UserDetailsLoading extends UserDetailsState {}

class UserDetailsLoaded extends UserDetailsState {
  final Map<String, dynamic> userDetails;

  UserDetailsLoaded(this.userDetails);

  @override
  List<Object?> get props => [userDetails];
}

class UserDetailsError extends UserDetailsState {
  final String message;

  UserDetailsError(this.message);

  @override
  List<Object?> get props => [message];
}

my user details bloc

class UserDetailsBloc extends Bloc<UserDetailsEvent, UserDetailsState> {
  UserDetailsBloc() : super(UserDetailsInitial());

  Stream<UserDetailsState> mapEventtoState(UserDetailsEvent event) async* {
    if (event is FetchUserDetails) {
      yield UserDetailsLoading();
      try {
        final fetchedDetails = await fetchUserDetailsFromStorage(event);
        print('user details fetched: $fetchedDetails');
        yield UserDetailsLoaded(fetchedDetails.toJson());
      } catch (e) {
        yield UserDetailsError('Failed to fetch user details: $e');
      }
    }
  }

  Future<UserDetails> fetchUserDetailsFromStorage(
      FetchUserDetails event) async {
    // Implement the logic to fetch user details from secure storage or an API
    // Return the fetched details
    const storage = FlutterSecureStorage();

    try {
      String? storedUsername = await storage.read(key: 'userName');
      String? storedPassword = await storage.read(key: 'pin');

      if (storedUsername != null && storedPassword != null) {
        // Create a UserDetails instance with the retrieved credentials
        UserDetails userDetails = UserDetails(
          username: storedUsername,
          password: storedPassword,
          deviceId: event.deviceId,
          ipAddress: event.ipAddress,
          appVersion: event.appVersion,
          platform: event.platform,
        );

        // Fetch the user details from the repository
        UserDetails fetchedUserDetails =
            await UserDetailsRepository().getUserDetails(userDetails);
        return fetchedUserDetails;
      } else {
        throw Exception('Stored credentials not found');
      }
    } catch (e) {
      throw Exception('Failed to fetch user details: $e');
    }
  }
}