hii我是新的Flutter和面临以下错误

final String title;
final String desc;
final String timer;
const ListElement({Key? key, required this.title, required this.desc ,required this.timer}) : 
super(key: key);

这是我的构造函数，我在其中传递了title desc和timer

Text(title, style: TextStyle(fontWeight: FontWeight.w400 ,
                  fontSize: 30),),
 Text(desc, style: TextStyle(fontWeight: FontWeight.w400 ,
                  fontSize: 15),),

获取标题和说明时遇到此错误