ESM-v2: Fix batch item failure message and reference to unbound variable (localstack#11495)

Author: gregfurman

localstack-core/localstack/services/lambda_/event_source_mapping/senders/lambda_sender.py

@@ -49,8 +49,7 @@ def send_events(self, events: list[dict]) -> dict:
             **optional_qualifier,
         )
         payload = json.load(invoke_result["Payload"])
-        if "FunctionError" in invoke_result:
-            function_error = invoke_result["FunctionError"]
+        if function_error := invoke_result.get("FunctionError"):
             LOG.debug(
                 "Pipe target function %s failed with FunctionError %s. Payload: %s",
                 self.target_arn,
@@ -85,8 +84,6 @@ def send_events(self, events: list[dict]) -> dict:
                 "requestId": invoke_result["ResponseMetadata"]["RequestId"],
                 "exceptionType": "BadRequest",
                 "resourceArn": self.target_arn,
-                "functionError": function_error,
-                "executedVersion": invoke_result.get("ExecutedVersion", "$LATEST"),
             }
             raise PartialFailureSenderError(error=error, partial_failure_payload=payload)