Handle render.ams with nil serializer or adapter

lib/active_model/serializer.rb

@@ -20,6 +20,7 @@ module ActiveModel
   class Serializer
     extend ActiveSupport::Autoload
     autoload :Adapter
+    autoload :Null
     include Configuration
     include Associations
     include Attributes

lib/active_model/serializer/null.rb

@@ -0,0 +1,17 @@
+module ActiveModel
+  class Serializer
+    class Null < Serializer
+      def attributes(*)
+        {}
+      end
+
+      def associations(*)
+        {}
+      end
+
+      def serializable_hash(*)
+        {}
+      end
+    end
+  end
+end

lib/active_model_serializers/logging.rb

@@ -81,7 +81,10 @@ def notify_render(*)
     end
 
     def notify_render_payload
-      { serializer: serializer, adapter: adapter }
+      {
+        serializer: serializer || ActiveModel::Serializer::Null,
+        adapter: adapter || ActiveModelSerializers::Adapter::Null
+      }
     end
 
     private