title: DRF JSONRenderer 'ReturnList' object has no attribute 'get'
body: <p>I am trying to follow a tutorial for <code>Django Rest Framework</code> and <code>VueJS</code> to make them work together. While using <code>JSONRenderer</code> <code>render</code> function is now giving me an issue of:</p>
  
  <pre><code>AttributeError: 'ReturnList' object has no attribute 'get'
  </code></pre>
  
  <p>My list view is :</p>
  
  <pre><code>from rest_framework import status
  from rest_framework.generics import ListAPIView, RetrieveAPIView
  from rest_framework.permissions import AllowAny
  from rest_framework.response import Response
  from .models import Cat
  from .renderers import CatJSONRenderer
  from .serializers import CatSerializer, CatListSerializer
  class CatListApiView(ListAPIView):
      model = Cat
      queryset = Cat.objects.all()
      permissions_classes = (AllowAny, )
      renderer_classes = (CatJSONRenderer, )
      serializer_class = CatListSerializer
  </code></pre>
  
  <p>My renderers.py is:</p>
  
  <pre><code>class CatJSONRenderer(JSONRenderer):
      charset = 'utf-8'
      def render(self, data, media_type=None, renderer_context=None):
          print(data)
          errors = data.get('errors', None)
  
          if errors is not None:
              return super(CatJSONRenderer, self).render(data)
  
          return json.dumps({'cats': data})
  </code></pre>
  
  <p>And Traceback is:</p>
  
  <pre><code>Traceback:
  
  File "/home/ytsejam/.virtualenvs/londonyogavidya/lib/python3.7/site-packages/django/core/handlers/exception.py" in inner
    34.             response = get_response(request)
  
  File "/home/ytsejam/.virtualenvs/londonyogavidya/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
    156.                 response = self.process_exception_by_middleware(e, request)
  
  File "/home/ytsejam/.virtualenvs/londonyogavidya/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
    154.                 response = response.render()
  
  File "/home/ytsejam/.virtualenvs/londonyogavidya/lib/python3.7/site-packages/django/template/response.py" in render
    106.             self.content = self.rendered_content
  
  File "/home/ytsejam/.virtualenvs/londonyogavidya/lib/python3.7/site-packages/rest_framework/response.py" in rendered_content
    72.         ret = renderer.render(self.data, accepted_media_type, context)
  
  File "/home/ytsejam/public_html/londoner/yogavidya/apps/cat/renderers.py" in render
    7.         errors = data.get('errors', None)
  
  Exception Type: AttributeError at /api/cats/
  Exception Value: 'ReturnList' object has no attribute 'get'
  </code></pre>
  
  <p>How can I solve this problem ? Thanks</p>