The getter 'state' was called on null.

edit_address.dart

class EditAddressForm extends StatefulWidget {
  final AccountBloc accountBloc;
  EditAddressForm(this.accountBloc, {Key key})
      : super(key: key);

  @override
  State<EditAddressForm> createState() =>
      _EditAddressFormState(accountBloc);
}

class _EditAddressFormState extends State<EditAddressForm> {
  final _formKey = GlobalKey<FormState>();
  final _addressController = TextEditingController();
  final _provinceController = TextEditingController();
  final _regencyController = TextEditingController();
  final _subDistrictController = TextEditingController();
  final _villageController = TextEditingController();
  final AccountBloc accountBloc;
  bool _inProgress = false;
  StoreLocation address;
  StreamSubscription subs;
  BuildContext _context;
  Map<String, String> territory = Map();

  _EditAddressFormState(this.accountBloc) {
    subs = accountBloc.state.listen((AccountState state) {
      if (state is AddressUpdated) {
        Navigator.pop(_context, true);
      } else if (state is EditAddressFailure) {
        Scaffold.of(_context).showSnackBar(
          SnackBar(
            content: Text(state.error),
            backgroundColor: Colors.red,
          ),
        );
      }
    });
  }

  @override
  void dispose() {
    super.dispose();
    subs.cancel();
  }

  @override
  Widget build(BuildContext context) {
    disableApiErrorHandler();

    _onAddressButtonPressed() {
      accountBloc.dispatch(EditAddress({
        "address": _addressController.text,
        "province": _provinceController.text,
        "regency": _regencyController.text,
        "sub_district": _subDistrictController.text,
        "village": _villageController.text,
      }));
    }

    return BlocBuilder<TerritoryBloc, TerritoryState>(
      builder: (context, state) {
        return Center(
          child: ListView(
            children: <Widget>[
              Padding(
                padding: EdgeInsets.all(10.0),
                child: Form(
                  key: _formKey,
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    mainAxisAlignment: MainAxisAlignment.start,
                    children: <Widget>[
                      Padding(
                        padding: EdgeInsets.only(top: 16, bottom: 10),
                        child: Text(
                          'Alamat Lengkap',
                          style: TextStyle(fontWeight: FontWeight.bold),
                        ),
                      ),
                      BaseFormField(
                        controller: _addressController,
                        hintText: "Alamat Lengkap",
                      ),
                      TerritoryDropdownView(
                        onSelectTerritory: (value, type) {
                          switch (type) {
                            case TerritoryType.province:
                              _provinceController.text = value.name;
                              break;
                            case TerritoryType.district:
                              _regencyController.text = value.name;
                              break;
                            case TerritoryType.subDistrict:
                              _subDistrictController.text = value.name;
                              break;
                            case TerritoryType.village:
                              _villageController.text = value.name;
                          }
                        },
                        territory: territory ?? Map(),
                      ),
                      Row(
                        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                        children: <Widget>[
                          Padding(
                            padding: EdgeInsets.only(top: 30.0, bottom: 20.0),
                            child: ButtonTheme(
                              // minWidth: MediaQuery.of(context).size.width,
                              child: RaisedButton(
                                  onPressed: () {
                                    // Navigator.of(context).push(null);
                                  },
                                  child: new Text(
                                    "Batalkan".toUpperCase(),
                                    style: TextStyle(color: Colors.grey),
                                  ),
                                  shape: new RoundedRectangleBorder(
                                      side: BorderSide(color: Colors.grey)),
                                  color: Colors.white),
                            ),
                          ),
                          Padding(
                            padding: EdgeInsets.only(top: 30.0, bottom: 20.0),
                            child: ButtonTheme(
                              // minWidth: MediaQuery.of(context).size.width,
                              child: RaisedButton(
                                onPressed: !_inProgress
                                    ? _onAddressButtonPressed
                                    : null,
                                child: new Text(
                                  "Simpan".toUpperCase(),
                                  style: TextStyle(color: Colors.white),
                                ),
                                shape: new RoundedRectangleBorder(
                                    side: BorderSide(color: Color(0xff039fc0))),
                                color: Color(0xff039fc0),
                              ),
                            ),
                          ),
                        ],
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),
        );
      },
    );
  }
}