Type error : type 'List<dynamic>' is not a subtype of type 'List<Map<String, dynamic>>' – Flutter

I’m working on an Flutter app that fetch the details of furniture from an API. I’ve to fetch 3 endpoints (/chairs, /sofas, / furnis) from the API.

So, I’ve definded _getAllFurnis() method is to make an HTTP GET request to retrieve data from three API endpoints for chairs, sofas, and furniture. If the response status code is 200 (successful), it decodes the response body into three lists of JSON objects, then converts them into lists of Furni objects and adds them to the corresponding empty List variables defined earlier. Finally, it sets _futureFurnis to a list containing these three lists of Furni objects.

Here is my entire code of the page api_shop_page.dart :

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:furnish_ar/models/Furni.dart';
import 'package:furnish_ar/pages/intro_page.dart';
import 'package:furnish_ar/pages/shop_page.dart';
import 'package:http/http.dart' as http;

class ApiShopPage extends StatefulWidget {
  const ApiShopPage({super.key});

  @override
  State<ApiShopPage> createState() => _ApiShopPageState();
}

class _ApiShopPageState extends State<ApiShopPage> {
   List<Furni> chairs = [];
   List<Furni> sofas = [];
   List<Furni> furnis = [];
   Future<List<List<Furni>>> _futureALLFurnis = [] as Future<List<List<Furni>>>;

   Future<List<List<Furni>>> _getAllFurnis() async {
       List<Map<String, dynamic>> jsonChairs = [];
       List<Map<String, dynamic>> jsonSofas = [];
       List<Map<String, dynamic>> jsonFurni = [];
       var chairUrl = "https://furnish-ar-api-s.vercel.app/chairs";
       var sofaUrl = "https://furnish-ar-api-s.vercel.app/sofas";
       var furniUrl = "https://furnish-ar-api-s.vercel.app/furnis";
       http.Response chairResponse = await http.get(Uri.parse(chairUrl));
       http.Response sofaResponse = await http.get(Uri.parse(sofaUrl));
       http.Response furniResponse = await http.get(Uri.parse(furniUrl));
       if (chairResponse.statusCode == 200 && sofaResponse.statusCode == 200 &&
           furniResponse.statusCode == 200) {
         String chairJsonData = chairResponse.body;
         String sofaJsonData = sofaResponse.body;
         String furniJsonData = furniResponse.body;

         jsonChairs = jsonDecode(chairJsonData);
         jsonSofas = jsonDecode(sofaJsonData);
         jsonFurni = jsonDecode(furniJsonData);

         for (Map<String, dynamic> index in jsonChairs) {
            chairs.add(Furni.fromJson(index));
         }   
         for (Map<String, dynamic> index in jsonSofas) {
            sofas.add(Furni.fromJson(index));
         }
         for (Map<String, dynamic> index in jsonFurni) {
            furnis.add(Furni.fromJson(index));
         }
        _futureAllFurnis = [chairs, sofas, furnis] as Future<List<List<Furni>>>;
      }
      return _futureAllFurnis;
    }

    @override
    Widget build(BuildContext context) {
       return Scaffold(
          body: FutureBuilder(
            future: _getAllFurnis(),
            builder: (context, snapshot) {
               if (snapshot.hasError) {
                   return Center(
                      child: Text(snapshot.error.toString()),
                   );  
               }

               if (snapshot.hasData && snapshot.data != null) {
                     List<List<Furni>> furnis = snapshot.data!;
                     return ShopPage(
                         chairs: furnis[0], sofas: furnis[1], furnis: furnis[2]);
               }

               return Center(
               child: CircularProgressIndicator();
        
            );
         },
      ),
    );
  }
}

The ShopPage widget is imported from a separate file and takes the lists of Furni objects as props to render a list of furniture items categorized as chairs, sofas, or other furniture items.

And I’ve Furni.fromJson() method :

factory Furni.fromJson(Map<dynamic, dynamic> json) => Furni(
    dimension: Dimension.fromJson(json["dimension"]),
    id: json["_id"],
    title: json["title"],
    description: json["description"],
    imageUrl: json["image_url"],
    modelUrl: json["model_url"],
    category: json["category"],
    price: json["price"],
    currency: json["currency"],
    rating: json["rating"]?.toDouble(),
    createdAt: DateTime.parse(json["created_at"]),
    v: json["__v"],
  );

But, when i run my application, It give me an error in the UI :

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

Can anyone please explain me why I’m getting such errors. It’ll be highly appriciated.