我想把数据库中的产品（条目）id作为代码中对象的['id']，但我得到了这个错误codedatabase

Future<void> fetchAndSetProducts() async {
    final url =
        Uri.parse('https://flutter-update.firebaseio.com/products.json');
    try {
      final response = await http.get(url);
      final extractedData = json.decode(response.body) as Map<String, dynamic>;
      final List<Product> loadedProducts = [];
      extractedData.forEach((prodId, prodData) {
        loadedProducts.add(Product(
          id: prodId,
          title: prodData['title'],
          description: prodData['description'],
          price: prodData['price'],
          isFavorite: prodData['isFavorite'],
          imageUrl: prodData['imageUrl'],
        ));
      });
      _items = loadedProducts;
      notifyListeners();
    } catch (error) {
      throw (error);
    }
  }