fix: Check that description is not None before checking content

Author: jabesq

internal-enrichment/shadowtrackr/src/shadowtrackr.py

@@ -153,7 +153,7 @@ def _process_entity(self, stix_objects, stix_entity, opencti_entity) -> str:
             else:
                 description = opencti_entity["x_opencti_description"]
 
-            if "[ShadowTrackr] " in description:
+            if description is not None and "[ShadowTrackr] " in description:
                 return (
                     "This ip is already processed by the ShadowTrackr connector. We're not doing it again,"
                     " that might mess up the score"