type 'String' is not a subtype of type 'Map<String, dynamic>' flutter

// To parse this JSON data, do
//
//     final economylistXml = economylistXmlFromJson(jsonString);

import 'dart:convert';

EconomylistXml economylistXmlFromJson(String str) => EconomylistXml.fromJson(json.decode(str));

String economylistXmlToJson(EconomylistXml data) => json.encode(data.toJson());

class EconomylistXml {
  EconomylistXml({
    required this.rss,
  });

  Rss rss;

  factory EconomylistXml.fromJson(Map<String, dynamic> json) => EconomylistXml(
    rss: Rss.fromJson(json["rss"]??""),
  );

  Map<String, dynamic>? toJson() => {
    "rss": rss.toJson(),
  };
}

class Rss {
  Rss({
    required this.empty,
    required this.channel,
  });

  Empty empty;
  Channel channel;

  factory Rss.fromJson(Map<String, dynamic> json) => Rss(
    empty: Empty.fromJson(json["\u0024"]??""),
    channel: Channel.fromJson(json["channel"]??""),
  );

  Map<String, dynamic>? toJson() => {
    "\u0024": empty.toJson(),
    "channel": channel.toJson(),
  };
}

class Channel {
  Channel({
    required this.title,
    required this.link,
    required this.description,
    required this.language,
    required this.copyright,
    required this.image,
    required this.item,
  });

  String? title;
  String? link;
  String? description;
  String? language;
  String? copyright;
  Image image;
  List<Item> item;

  factory Channel.fromJson(Map<String, dynamic> json) => Channel(
    title: json["title"]??"",
    link: json["link"]??"",
    description: json["description"]??"",
    language: json["language"]??"",
    copyright: json["copyright"]??"",
    image: Image.fromJson(json["image"]??""),
    item: List<Item>.from(json["item"].map((x) => Item.fromJson(x))??""),
  );

  Map<String, dynamic>? toJson() => {
    "title": title,
    "link": link,
    "description": description,
    "language": language,
    "copyright": copyright,
    "image": image.toJson(),
    "item": List<dynamic>.from(item.map((x) => x.toJson())),
  };
}

class Image {
  Image({
    required this.title,
    required this.url,
    required this.link,
    required this.width,
    required this.height,
  });

  String? title;
  String? url;
  String? link;
  String? width;
  String? height;

  factory Image.fromJson(Map<String, dynamic> json) => Image(
    title: json["title"]??"",
    url: json["url"]??"",
    link: json["link"]??"",
    width: json["width"]??"",
    height: json["height"]??"",
  );

  Map<String, dynamic>? toJson() => {
    "title": title,
    "url": url,
    "link": link,
    "width": width,
    "height": height,
  };
}

class Item {
  Item({
    required this.title,
    required this.description,
    required this.link,
    required this.pubDate,
  });

  String? title;
  String? description;
  String? link;
  String? pubDate;

  factory Item.fromJson(Map<String, dynamic> json) => Item(
    title: json["title"]??"",
    description: json["description"]??"",
    link: json["link"]??"",
    pubDate: json["pubDate"]??"",
  );

  Map<String, dynamic>? toJson() => {
    "title": title,
    "description": description,
    "link": link,
    "pubDate": pubDate,
  };
}

class Empty {
  Empty({
    required this.version,
  });

  String? version;

  factory Empty.fromJson(Map<String, dynamic> json) => Empty(
    version: json["version"]??"",
  );

  Map<String, dynamic>? toJson() => {
    "version": version,
  };
}

import 'package:flutter/material.dart';
import 'package:halkaarzhisseler/models/apis/economy_api.dart';
import 'package:http/http.dart' as http;

import '../models/apis/economy_xml.dart';
import 'haberdetail.dart';


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

  @override
  State<Economy> createState() => _EconomyState();
}

class _EconomyState extends State<Economy> {
  ScrollController? controller;
  final scaffoldKey = GlobalKey<ScaffoldState>();
  final url = Uri.parse('https://v1.nocodeapi.com/miktadtahir/xml_to_json/htvLvoPDCwIEyTxa?url=https://ekonomigundemi.com.tr/rss/ekonomi/246.xml');
  var counter;
  EconomylistXml? haberResult;

  Future callHaber() async {
    try{

      final response = await http.get(url);

      if(response.statusCode == 200){
        var rss = economylistXmlFromJson(response.body);

        if(mounted);
        setState(() {
          counter = haberResult?.rss.channel.item.length;//<--- here
          haberResult = rss;
        });
        return rss;
      } else {
        print(response.statusCode);
      }
    } catch(e) {
      print(e.toString());
    }
  }
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    callHaber();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        centerTitle: false,
        automaticallyImplyLeading: false,
        title: Text(
            'Ekonomi Haberleri'
        ),
      ),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: counter != null ?

          ListView.builder(
              itemCount: counter,
              itemBuilder: (context, index){
                return Card(
                  child: ListTile(
                    title: Text(haberResult?.rss.channel.item[index].title??""),
                    leading: CircleAvatar(
                      backgroundImage: NetworkImage(haberResult?.rss.channel.item[index].description??""),),


                    onTap: () => Navigator.push(
                      context, MaterialPageRoute(builder: (context) => HaberDetailScreen( subtitle: haberResult?.rss.channel.item[index].title??"", title: haberResult?.rss.channel.item[index].description??"")),),
                  ),
                );
              }) : Center(child: CircularProgressIndicator(

          )),
        ),
      ),
    );

  }
}