Solving _InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'String

Hello everyone I have this error when trying to acces to a product from another route than the main route ( trying from scanner QR. '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'String'.

The main route is working fine & this error only happen to variable product.

This is the call of the widget and the first error

           Consumer<ProductManagmentModel>(
                    builder: (_, model, __) {
                      if (model.product!.type != 'variable') {
                        return const SizedBox();
                      }
                      return VariationWidget(
                        variations: model.product!.variationProducts ?? [],
                        productAttributes: model.product!.vendorAdminProductAttributes,
                        onUpdate: (list) {
                          model.updateVariations(list);
                        },
                      );
                    },
                  ),

Where does the second error come from in the Variation_Widget.dart at line opts.add(attr.options![i]);

 List<ProductVariation> _generateVariations() {
    var _variations = <ProductVariation>[];
    var options = <List<String>>[];
    var slugs = <List<String>>[];
    var attrNames = <String>[];
    for (var attr in productAttributes) {
      if (!(attr.isActive ?? false)) {
        continue;
      }
      if (!(attr.isVariation ?? false)) {
        continue;
      }
      var opts = <String>[];
      var sls = <String>[];

      for (var i = 0; i < attr.options!.length; i++) {
        opts.add(attr.options![i]);
        sls.add(attr.optionSlugs[i]);
      }
      options.add(opts);
      slugs.add(sls);

      attrNames.add(attr.slug ?? '');
    }
    final list = combinations(options, slugs, attrNames).map((e) => e.toList()).toList();

    for (var item in list) {
      if (item.isNotEmpty) {
        var variation = ProductVariation()..attributeList = item;
        _variations.add(variation);
      }
    }

    return _variations;
  }

This is where the data are parsed from API (product.dart)

    if (parsedJson['attributesData'] != null) {
        try {
          parsedJson['attributesData'].forEach((element) =>
              vendorAdminProductAttributes
                  .add(ProductAttribute.fromJson(element)..isActive = true));
        } catch (e) {
          printLog(e);
        }
      }

      if (parsedJson['variation_products'] != null) {
        for (var item in parsedJson['variation_products']) {
          vendorAdminVariations.add(VendorAdminVariation.fromJson(item));
        }
      } 

Thank you for any help i'am block with the scanner QR since 2 weeks