Return always an empty object (#39)

Author: adinhodovic

django_google_optimize/middleware.py

@@ -5,7 +5,7 @@
 
 def google_optimize(get_response):
     def middleware(request):
-        request.google_optimize = get_experiments_variants(request)
+        request.google_optimize = get_experiments_variants(request) or {}
         return get_response(request)
 
     return middleware