Fix call to is_jwt_authenticated when the request has no successful_a…

…uthenticator attribute

edx_rest_framework_extensions/__init__.py

@@ -1,3 +1,3 @@
 """ edx Django REST Framework extensions. """
 
-__version__ = '2.3.0'  # pragma: no cover
+__version__ = '2.3.1'  # pragma: no cover

edx_rest_framework_extensions/auth/jwt/authentication.py

@@ -77,10 +77,13 @@ def authenticate_credentials(self, payload):
 
 
 def is_jwt_authenticated(request):
-    is_jwt_authenticated = issubclass(
-        type(request.successful_authenticator),
-        BaseJSONWebTokenAuthentication,
-    )
+    is_jwt_authenticated = False
+    successful_authenticator = getattr(request, 'successful_authenticator', None)
+    if successful_authenticator:
+        is_jwt_authenticated = issubclass(
+            type(successful_authenticator),
+            BaseJSONWebTokenAuthentication
+        )
     if is_jwt_authenticated:
         if not getattr(request, 'auth', None):
             logger.error(