Выдает ошибку TypeError at /api/users/subscriptions/ object of type 'function' has no len() помогите пожалуйста исправить

у меня не высвечивается мои подписки на сайте.в админке подписки видны. переходишь на сайт подписки выдает ошибку

.api/users/subscriptions/?page=1&limit=6&recipes_limit=3 500 (Internal Server Error)
value @ index.js:273
index.js:20
index.js:28
zu @ react-dom.production.min.js:262
t.unstable_runWithPriority @ scheduler.production.min.js:18
Wo @ react-dom.production.min.js:122
Lu @ react-dom.production.min.js:261
yu @ react-dom.production.min.js:243
react-dom.production.min.js:123
t.unstable_runWithPriority @ scheduler.production.min.js:18
Wo @ react-dom.production.min.js:122
qo @ react-dom.production.min.js:123
Qo @ react-dom.production.min.js:122
Re @ react-dom.production.min.js:292
Xt @ react-dom.production.min.js:73
VM510:1  Uncaught (in promise) SyntaxError: Unexpected token 'T', "TypeError "... is not valid JSON

views.py

class UserSubscribeViewSet(UserViewSet):
    permission_classes = (IsAuthenticatedOrReadOnly,)
    pagination_class = CustomPageNumberPagination

    @action(
        detail=False,
        methods=('get',),
        serializer_class=SubscriptionSerializer,
        permission_classes=(IsAuthenticated, )
    )
    def subscriptions(self, request):
        user = self.request.user
        user_subscriptions = user.subscriber.all()
        authors = [item.author.id for item in user_subscriptions]
        queryset = User.objects.filter(pk__in=authors)
        queryset = self.filter_queryset(queryset)
        paginated_queryset = self.paginate_queryset(queryset)
        serializer = self.get_serializer(paginated_queryset, many=True)

        return self.get_paginated_response(serializer.data)

Перебрал все,что мог.serialazer

class SubscriptionSerializer(CustomUserSerializer):
    recipes = SerializerMethodField(method_name='get_recipes')
    recipes_count = SerializerMethodField(
        method_name='get_recipes_count'
    )

    def get_srs(self):
        from recipes.serializers.shortrecipes import ShortRecipeSerializer

        return ShortRecipeSerializer

    def get_recipes(self, obj):
        author_recipes = Recipe.objects.filter(author=obj)

        if 'recipes_limit' in self.context.get('request').GET:
            recipes_limit = self.context.get('request').GET['recipes_limit']
            author_recipes = author_recipes[:int(recipes_limit)]

        if author_recipes:
            serializer = self.get_srs()(
                author_recipes,
                context={'request': self.context.get('request')},
                many=True
            )
            return serializer.data

        return []

    def get_recipes_count(self, obj):
        return Recipe.objects.filter(author=obj).count()

    class Meta:
        model = User
        fields = ('email', 'id', 'username', 'first_name', 'last_name',
                  'is_subscribed', 'recipes', 'recipes_count')

getSubscriptions ({ page, limit = 6, recipes_limit = 3 }) { const token = localStorage.getItem('token') return fetch( /api/users/subscriptions/?page=${page}&limit=${limit}&recipes_limit=${recipes_limit}, { method: 'GET', headers: { ...this._headers, 'authorization': Token ${token} } } ).then(this.checkResponse) }

вот показывает тут ошибка . действительно это так? Ёще код ошибок

Traceback:

File "/usr/local/lib/python3.7/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/usr/local/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python3.7/site-packages/django/views/decorators/csrf.py" in wrapped_view
  54.         return view_func(*args, **kwargs)

File "/usr/local/lib/python3.7/site-packages/rest_framework/viewsets.py" in view
  125.             return self.dispatch(request, *args, **kwargs)

File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py" in dispatch
  509.             response = self.handle_exception(exc)

File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py" in handle_exception
  469.             self.raise_uncaught_exception(exc)

File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py" in raise_uncaught_exception
  480.         raise exc

File "/usr/local/lib/python3.7/site-packages/rest_framework/views.py" in dispatch
  506.             response = handler(request, *args, **kwargs)

File "/app/users/views.py" in subscriptions
  47.         paginated_queryset = self.paginate_queryset(queryset)

File "/usr/local/lib/python3.7/site-packages/rest_framework/generics.py" in paginate_queryset
  171.         return self.paginator.paginate_queryset(queryset, self.request, view=self)

File "/usr/local/lib/python3.7/site-packages/rest_framework/pagination.py" in paginate_queryset
  204.             self.page = paginator.page(page_number)

File "/usr/local/lib/python3.7/site-packages/django/core/paginator.py" in page
  70.         number = self.validate_number(number)

File "/usr/local/lib/python3.7/site-packages/django/core/paginator.py" in validate_number
  48.         if number > self.num_pages:

File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py" in __get__
  80.         res = instance.__dict__[self.name] = self.func(instance)

File "/usr/local/lib/python3.7/site-packages/django/core/paginator.py" in num_pages
  97.         if self.count == 0 and not self.allow_empty_first_page:

File "/usr/local/lib/python3.7/site-packages/django/utils/functional.py" in __get__
  80.         res = instance.__dict__[self.name] = self.func(instance)

File "/usr/local/lib/python3.7/site-packages/django/core/paginator.py" in count
  92.         return len(self.object_list)