BatchProcessor.response() crashes with KeyError when failed SQS record lacks messageId

[KirtiRamchandani]

Bug

When raise_on_entire_batch_failure=False and a record handler throws, BatchProcessor.response() can crash with:

KeyError: 'messageId'

in _collect_sqs_failures() via msg.message_id.

This happens if the inbound SQS record is missing messageId (malformed/custom event injection).

Repro

from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType

processor = BatchProcessor(event_type=EventType.SQS, raise_on_entire_batch_failure=False)

def record_handler(record):
    raise RuntimeError("boom")

bad_record = {
    "body": "{}",
    "receiptHandle": "rh",
    "attributes": {"ApproximateReceiveCount": "1"},
    "messageAttributes": {},
    "md5OfBody": "abc",
    "eventSource": "aws:sqs",
    "eventSourceARN": "arn:aws:sqs:us-east-1:123:q",
    "awsRegion": "us-east-1",
}

with processor(records=[bad_record], handler=record_handler):
    processor.process()

processor.response()  # KeyError: 'messageId'

Expected

Return partial batch response (empty itemIdentifier or explicit error), not crash the Lambda.

Proof after fix

tests/functional/batch/required_dependencies/test_utilities_batch.py::test_sqs_batch_processor_missing_message_id_does_not_crash_on_handler_failure PASSED

PR incoming.

[boring-cyborg]

Thanks for opening your first issue here! We'll come back to you as soon as we can.
In the meantime, check out the #python channel on our Powertools for AWS Lambda Discord: Invite link