未显示颤动TextFormField验证，并给出非活动InputConnections的错误

TextFormField(
  validator: (value) {
    if (value == null || value.isEmpty) {
      return 'Please enter some text';
    }
    return null;
  },
  decoration: InputDecoration(
    labelText: 'Enter Text',
  ),
),

class MyFormWidget extends StatefulWidget {
  @override
  _MyFormWidgetState createState() => _MyFormWidgetState();
}

class _MyFormWidgetState extends State<MyFormWidget> {
  final _formKey = GlobalKey<FormState>();

  @override
  void dispose() {
    // 释放InputConnections
    FocusScope.of(context).unfocus();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            validator: (value) {
              if (value == null || value.isEmpty) {
                return 'Please enter some text';
              }
              return null;
            },
            decoration: InputDecoration(
              labelText: 'Enter Text',
            ),
          ),
          ElevatedButton(
            onPressed: () {
              if (_formKey.currentState!.validate()) {
                // 处理表单提交
              }
            },
            child: Text('Submit'),
          ),
        ],
      ),
    );
  }
}

TextFormField(
  validator: (value) {
    print('Validating...');
    if (value == null || value.isEmpty) {
      return 'Please enter some text';
    }
    return null;
  },
  decoration: InputDecoration(
    labelText: 'Enter Text',
  ),
),