Avoid throwing exceptions with the default exception handler

Author: jsenecal

rest_framework_json_api/renderers.py

@@ -47,7 +47,7 @@ def render(self, data, accepted_media_type=None, renderer_context=None):
 
         # If this is an error response, skip the rest.
         if resource_name == 'errors':
-            if len(data) > 1:
+            if len(data) > 1 and isinstance(data, list):
                 data.sort(key=lambda x: x.get('source', {}).get('pointer', ''))
             return super(JSONRenderer, self).render(
                 {resource_name: data}, accepted_media_type, renderer_context