fix nonetype error check by checking if not none

Author: notque

auditmiddleware/_api.py

@@ -453,6 +453,7 @@ def _create_events(self, target_project, res_id,
 
                 # attach payload if requested
                 if self._payloads_enabled and res_spec.payloads['enabled'] \
+                   and request.content_length is not None \
                    and request.content_length > 0 \
                    and request.content_type == "application/json":
                     req_pl = request.json