early exit in is_legacy_lambda_step_function

Author: avedmala

datadog_lambda/tracing.py

@@ -411,10 +411,10 @@ def is_legacy_lambda_step_function(event):
     """
     Check if the event is a step function that called a legacy lambda
     """
-    if not isinstance(event, dict):
+    if not isinstance(event, dict) or "Payload" not in event:
         return False
 
-    event = event.get("Payload", {})
+    event = event.get("Payload")
     return "Execution" in event and "StateMachine" in event and "State" in event