Unsupported opertion: _Namespace란

사진을 선택하면 Unsupported opertion: _Namespace란 화면이 뜨면서 아래와 같이 나오네요. 

null safty 문제는 해결했는데 몇 일째 겔러리에서 사진 불러오기에서 못넘어가고있네요. ㅠ 

sdk: 2.12.0 버전 쓰고있습니다.

import 'dart:io';

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';

class CreatePage extends StatefulWidget {
  const CreatePage({Key? key}) : super(key: key);

  @override
  _CreatePageState createState() => _CreatePageState();
}

class _CreatePageState extends State<CreatePage> {
  final textEditingController = TextEditingController();

  // ignore: unused_field
  File? _image;
  final picker = ImagePicker();

  @override
  void dispose() {
    textEditingController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: _buildAppBar(),
      body: _buildBody(),
      floatingActionButton: FloatingActionButton(
          onPressed: _getImage, child: Icon(Icons.add_a_photo)),
    );
  }

  PreferredSizeWidget _buildAppBar() {
    return AppBar(
      title: Center(
        child: Text('새 게시물',
            style: TextStyle(color: Colors.black, fontWeight: FontWeight.bold)),
      ),
      actions: [
        IconButton(
          icon: Icon(Icons.send),
          onPressed: () {},
        )
      ],
    );
  }

  Future _getImage() async {
    print('object');
    var image = await picker.pickImage(source: ImageSource.gallery);

    setState(() {
      _image = File(image!.path);
    });
  }

  Widget _buildBody() {
    return SingleChildScrollView(
      child: Column(
        children: [
          _image == null ? Text('No Image') : Image.file(_image!),
          TextField(
            decoration: InputDecoration(hintText: '내용을 입력하세요'),
            controller: textEditingController,
          )
        ],
      ),
    );
  }
}