我正在一个项目中，我必须用从我们的Web服务读取的图标代码动态填充图标小部件。

问题是，当我处于调试模式时，一切正常，并且图标按预期显示，但是一旦我构建了生产版本apk，它就不再显示某些图标。这是我的小部件代码。

            @override
            Widget build(BuildContext context) {
              var theme = Theme.of(context);
              return Scaffold(
                backgroundColor: CustomColors.primaryVariant,appBar: AppBar(
                  title: Text(widget.title ?? ''),backgroundColor: CustomColors.primary,),body: Container(
                  color: CustomColors.primary,height: MediaQuery.of(context).size.height,child: Stack(
                    children: [
                      Visibility(
                        visible: items.length > 0,child: ListView.builder(
                          shrinkWrap: true,itemCount: items.length,itemBuilder: (context,index) {
                            var item = items[index];
                            return Card(
                              color: CustomColors.primaryVariant,elevation: 5.0,margin: new EdgeInsets.symmetric(vertical: .5),child: Container(
                                child: ListTile(
                                  leading: Container(
                                    padding: EdgeInsets.only(right: 12.0),decoration: new BoxDecoration(
                                        border: new Border(
                                            right: new BorderSide(
                                                width: 1.0,color: Colors.white24))),child: Icon(CustomIcon(item.code),color: Colors.white),title: Text(
                                    item.detail.capitalize(),style: TextStyle(color: Colors.white,fontSize: 16),subtitle: Text(
                                    item.item,style: TextStyle(color: Colors.white70,fontSize: 14),);
                          },Visibility(
                        visible: items.length == 0,itemCount: 4,index) {
                            return Card(
                              color: CustomColors.primaryVariant,child: ShimmerSkeleton(
                                      height: 20,width: 20,title: SizedBox(
                                    width: 60,width: 60,subtitle: Padding(
                                    padding: EdgeInsets.only(top: 5),child: ShimmerSkeleton(
                                      width: 90,Positioned(
                        bottom: 0,left: MediaQuery.of(context).size.width * 0.5 - 130,child: Container(
                          margin: EdgeInsets.symmetric(vertical: 25),child: Opacity(
                            opacity: .8,child: SizedBox(
                              height: 60,width: MediaQuery.of(context).size.width,child: ListTile(
                                leading: CircleAvatar(
                                  radius: 26,backgroundImage: AssetImage('assets/img/rodal.jpg'),title: Text(
                                  'SUPPORTED BY',style: theme.textTheme.title.copyWith(
                                      fontWeight: FontWeight.w600,subtitle: Text(
                                  'Rodaltech,SRL',fontSize: 20),)
                    ],);
            }
          }
          
          class CustomIcon extends IconData {
            CustomIcon(int codePoint) : super(codePoint,fontFamily: 'MaterialIcons');
          }

我的ItemDetail模型：

        class ItemDetail {
      ItemDetail({
        this.code,this.item,this.detail,});
    
      int code;
      String item;
      String detail;
    
      ItemDetail copyWith({
        int code,String item,String detail,}) =>
          ItemDetail(
            code: code ?? this.code,item: item ?? this.item,detail: detail ?? this.detail,);
    
      factory ItemDetail.fromJson(Map<String,dynamic> json) =>
          ItemDetail(
            code: json["code"] == null ? null : json["code"],item: json["item"] == null ? null : json["item"],detail: json["detail"] == null ? null : json["detail"],);
    
      Map<String,dynamic> toJson() => {
            "code": code == null ? null : code,"item": item == null ? null : item,"detail": detail == null ? null : detail,};
    }

还添加了调试模式和生产模式的屏幕截图：