The following is my event which get called when tapped on send code button after entering phone number

 on<sendOtpEvent>((event,emit)async{
         await _auth.verifyPhoneNumber(
          phoneNumber:event.number,
          verificationCompleted:(PhoneAuthCredential credentials){},
          verificationFailed: (FirebaseAuthException e) {
            emit(ErrorState(error: e.message.toString()));
          },
          codeSent: (String verificationId, int? forceResendingToken) async{
              
            },
          codeAutoRetrievalTimeout: (String verificationId) {
          });
    });

This is Login Screen Page on which the send code button will call the send otp event

TextEditingController _phoneController=TextEditingController();
  final _formKey = GlobalKey<FormState>();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: BlocBuilder<whatsAppBloc,whatsAppStates>(
        builder: (context,state){
            if(state is verifyOTPState){
              Navigator.pushReplacement(context,MaterialPageRoute(builder:(context)=>VerifyOTP(verificationID: state.verificationID, CurrentUserPhoneNumber:_phoneController.text)));
            }
            if(state is ErrorState)
              {
                ScaffoldMessenger.of(context).showSnackBar(SnackBar(content:Text(state.error.toString())));
              }
            return  SingleChildScrollView(
              child: SizedBox(
                height: MediaQuery.sizeOf(context).height,
                width: MediaQuery.sizeOf(context).width,
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    Image.asset(
                      "assets/Images/whatsapp.png",
                      scale: 4,
                    ),
                    RichText(
                        textAlign: TextAlign.center,
                        text: const TextSpan(children: [
                          TextSpan(
                              style: TextStyle(
                                  height: 2.5,
                                  fontFamily: "Helvetica",
                                  fontWeight: FontWeight.w600,
                                  color: Color.fromRGBO(89, 176, 114, 1),
                                  fontSize: 33),
                              text: "WhatsAppn"),
                          TextSpan(
                              style: TextStyle(
                                  height: 1.5,
                                  fontFamily: "Helvetica",
                                  color: Colors.black,
                                  fontSize: 14,
                                  fontWeight: FontWeight.normal),
                              text: "Enter your Phone Number nto continuen"),
                        ])),
                    Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Row(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Expanded(
                            flex: 1,
                            child: Container(
                              height: 55,
                              alignment: Alignment.center,
                              decoration: BoxDecoration(
                                  borderRadius: BorderRadius.circular(10),
                                  border: Border.all(color: Colors.grey)
                              ),
                              child: Text("+91",style: TextStyle(fontSize: 16,fontWeight:FontWeight.normal,fontFamily: "Helvetica"),),
                            ),
                          ),
                          SizedBox(width: 5,),
                          Expanded(
                            flex: 7,
                            child: Form(
                              key: _formKey,
                              child: TextFormField(
                                controller: _phoneController,
                                validator: (value) {
                                  if (value == null || value.length < 10) {
                                    return "Please enter a valid phone number";
                                  } else {
                                    return null;
                                  }
                                },
                                textAlign: TextAlign.start,
                                cursorColor: Colors.black,
                                style: const TextStyle(
                                    fontWeight: FontWeight.normal,
                                    fontFamily: "Helvetica",
                                    fontSize: 16),
                                decoration: InputDecoration(
                                  focusedBorder: OutlineInputBorder(borderRadius: BorderRadius.circular(10),borderSide: BorderSide(color: Colors.green)),
                                  border: OutlineInputBorder(borderRadius: BorderRadius.circular(10),borderSide: BorderSide(color: Colors.black)),
                                ),
                                keyboardType: TextInputType.phone,
                              ),
                            ),
                          ),
                        ],
                      ),
                    ),
                    ElevatedButton(
                        onPressed: () async{
                          if (_formKey.currentState!.validate() == true){
                             _formKey.currentState?.save();
                             BlocProvider.of<whatsAppBloc>(context).add(sendOtpEvent(context:context,number:"+91${_phoneController.text}"));
                          }
                        },
                        style: ElevatedButton.styleFrom(
                            elevation: 0,
                            shape: RoundedRectangleBorder(
                                borderRadius: BorderRadius.circular(12)),
                            backgroundColor: Color.fromRGBO(32, 152, 34, 1),
                            foregroundColor: Colors.white),
                        child: const Text(
                          "Send Code",
                          style: TextStyle(
                              fontFamily: "Helvetica",
                              fontSize: 15,
                              fontWeight: FontWeight.bold),
                        ))
                  ],
                ),
              ),
            );
       },
      ),
    );
  }

The following is my event for calling firebase phone auth

class sendOtpEvent extends whatsAppEvents{
  BuildContext context;
  String number;
  sendOtpEvent({required this.number,required this.context});
}

Following are my states which will get called by my events

class ErrorState extends whatsAppStates{
  String error;
  ErrorState({required this.error});
}
class verifyOTPState extends whatsAppStates{
  String verificationID;

  verifyOTPState({required this.verificationID});
}

I have tried with async with the codeSent body but it does not worked please provide solution to this error