May be a duplicate of https://github.com/localstack/localstack/issues/988 but due to the age I will re raise.

I'm having issues when I throw an exception in a lambda - it isn't appearing on my dead letter queue. Is there something I am missing, I would like an sqs event exception to appear on the poison queue when an exception happens.

Below is the basic config:
 ````
    sqsclient.create_queue(QueueName = 'test-queue')
    sqsclient.create_queue(QueueName = 'test-queue-poison')

    lambda_client.create_function(
            FunctionName='MyFunction',
            Runtime='dotnetcore2.1',
            Role='role',
            Handler='Handler',
            Code=code,
	    DeadLetterConfig={'TargetArn': 'test-queue-poison-arn'})

     lambda_client.create_event_source_mapping(
		EventSourceArn='test-queue-arn',
		FunctionName='MyFunction',
		Enabled=True,
		BatchSize=100,
		StartingPosition='LATEST')
````

So when I raise a new (.net)exception within the lambda function no message is going to the dead letter queue. I can confirm that all is attached together OK as all other scenarios work, and the above code is pseudo-ish.
import os
import json
import glob
import tempfile
import requests
import shutil
import zipfile
import importlib
from six import iteritems
from localstack.utils.aws import aws_stack
from localstack.constants import (LOCALSTACK_ROOT_FOLDER, LOCALSTACK_VENV_FOLDER,
    LAMBDA_TEST_ROLE, TEST_AWS_ACCOUNT_ID)
from localstack.utils.common import TMP_FILES, run, mkdir, to_str, save_file, is_alpine
from localstack.services.awslambda.lambda_api import (get_handler_file_from_name, LAMBDA_DEFAULT_HANDLER,
    LAMBDA_DEFAULT_RUNTIME, LAMBDA_DEFAULT_STARTING_POSITION, LAMBDA_DEFAULT_TIMEOUT)
ARCHIVE_DIR_PREFIX = 'lambda.archive.'
def copy_dir(source, target):