Erro ao criar na transferência

Aqui está o meu código atual:

import 'package:flutter/material.dart';

void main() => runApp(BytebankApp());

class BytebankApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: ListaTransferencias(),
      ),
    );
  }
}

class FormularioTransferencia extends StatefulWidget {





  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return FormularioTransferenciaState();
  }
}

class FormularioTransferenciaState extends State<ListaTransferencias> {

  final TextEditingController _controladorCampoNumeroConta = TextEditingController();
  final TextEditingController _controladorCampoValor = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: Text('Criando Transferência'),),
        body: SingleChildScrollView(
          child: Column(
            children: [
              Editor(controlador: _controladorCampoNumeroConta, dica: '0000', rotulo: 'Número da conta',),
              Editor(dica: '0.00', controlador: _controladorCampoValor, rotulo: 'Valor', icone: Icons.monetization_on,),
              ElevatedButton(
                child: Text('Confirmar'),
                onPressed: () => _criaTransferencia(context),
              )
            ],
          ),
        ));
  }
  void _criaTransferencia(BuildContext context) {
    final int? numeroConta = int.tryParse(_controladorCampoNumeroConta.text);
    final double? valor = double.tryParse(_controladorCampoValor.text);
    if (numeroConta != null && valor != null) {
      final transferenciaCriada = Transferencia(valor, numeroConta);
      debugPrint('Criando transferência');
      debugPrint('$transferenciaCriada');
      Navigator.pop(context, transferenciaCriada);
    };
  }
}


class Editor extends StatelessWidget {

  final TextEditingController? controlador;
  final String? rotulo;
  final String? dica;
  final IconData? icone;

  Editor({this.controlador, this.rotulo, this.dica, this.icone});

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: TextField(
        controller: controlador,
        style: TextStyle(
            fontSize: 24.0
        ),
        decoration: InputDecoration(
            icon: icone != null ?  Icon(icone) : null,
            labelText: rotulo,
            hintText: dica,
        ),
        keyboardType: TextInputType.number,
      ),
    );
  }
}


class ListaTransferencias extends StatefulWidget{
  final List<Transferencia> _transferencias = List.empty(growable: true);

  @override
  State<StatefulWidget> createState() {
    return ListaTransferenciasState();
  }
}

class ListaTransferenciasState extends State<ListaTransferencias> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Transferências'),
      ),
      body: ListView.builder(
        itemCount: widget._transferencias.length,
        itemBuilder: (context, indice) {
          final transferencia = widget._transferencias[indice];
          return ItemTransferencia(transferencia);
        },
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add), onPressed: () {
        final Future<Transferencia?> future = Navigator.push(context, MaterialPageRoute(builder: (context) {
          return FormularioTransferencia();
        }));
        future.then((transferenciaRecebida) {
          Future.delayed(Duration(seconds: 1), () {
            debugPrint('chegou no then do future');
            debugPrint('$transferenciaRecebida');
            if(transferenciaRecebida != null) {
              setState(() {
                widget._transferencias.add(transferenciaRecebida);
              });
            }
          });
        });
      },),
    );
  }
}

class ItemTransferencia extends StatelessWidget {

  final Transferencia _transferencia;

  ItemTransferencia(this._transferencia);

  @override
  Widget build(BuildContext context) {
    return Card(
      child: ListTile(
        leading: Icon(Icons.monetization_on),
        title: Text(_transferencia.valor.toString()),
        subtitle: Text(_transferencia.numeroConta.toString()),
      ),
    );
  }
}

class Transferencia {
  final double valor;
  final int numeroConta;

  Transferencia(this.valor, this.numeroConta);
  @override
  String toString() {
    return 'Transferencia{valor: $valor, numeroConta: $numeroConta}';
  }
}

A declaração está errada:

class FormularioTransferenciaState extends State<ListaTransferencias> {

deve ser

class FormularioTransferenciaState extends State<FormularioTransferencia> {

Agora funciona. Obrigado.