fix: handle missing user agent in request logs

apps/utils/mixins.py

@@ -466,7 +466,10 @@ class MyLoggingMixin(object):
 
     def _get_agent(self, request):
         """Get os string"""
-        return str(parse(request.META['HTTP_USER_AGENT']))
+        user_agent = request.META.get('HTTP_USER_AGENT', '')
+        if not user_agent:
+            return ''
+        return str(parse(user_agent))
 
     def _get_response_ms(self):
         """