fix: ensure setting operator to None (#16371) (#16372)

superset/jinja_context.py

@@ -297,7 +297,7 @@ class ExtraCache:
 
         for flt in form_data.get("adhoc_filters", []):
             val: Union[Any, List[Any]] = flt.get("comparator")
-            op: str = flt["operator"].upper() if "operator" in flt else None
+            op: str = flt["operator"].upper() if flt.get("operator") else None
             # fltOpName: str = flt.get("filterOptionName")
             if (
                 flt.get("expressionType") == "SIMPLE"