代码很干净，但是我运行后我收到了这个错误

Question

import 'package:flutter/material.dart';  
class CustomIcons {   
     static const IconData favorite = IconData(0xe900, fontFamily: "CustomIcon"); 
     static const IconData search = IconData(0xe901, fontFamily: "CustomIcon");
     static const IconData cart = IconData(0xe903, fontFamily: "CustomIcon"); 
}