Invalid constant value

Código do meu contact_form.dart:

import 'package:flutter/material.dart';

class ContactForm extends StatefulWidget {

  @override
  State<ContactForm> createState() => _ContactFormState();
}

class _ContactFormState extends State<ContactForm> {
  final TextEditingController _nameController = TextEditingController();
  final TextEditingController _accountNumberController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('New contact'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: const <Widget>[
            TextField(
              controller: _nameController,
              decoration: InputDecoration(
                labelText: 'Full name',
              ),
              style: TextStyle(fontSize: 24.0),
            ),
            Padding(
              padding: EdgeInsets.only(top: 8.0),
              child: TextField(
                controller: _accountNumberController,
                decoration: InputDecoration(
                  labelText: 'Account number',
                ),
                style: TextStyle(
                  fontSize: 24.0,
                ),
                keyboardType: TextInputType.number,
              ),
            ),
            Padding(
              padding: EdgeInsets.only(top: 8.0),
              child: SizedBox(
                width: double.maxFinite,
                child: ElevatedButton(
                  child: Text('Create'), onPressed: () {
                  final String name = _nameController.text;
                  final int accountNumber = int.tryParse(_accountNumberController.text);
                  },
           ),
              ),
            )
          ],
        ),
      ),
    );
  }
}

Remova o conts dechildren: const <Widget>[

Obrigado pela ajuda!