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.
TEST_STAGE_NAME = 'testing'
    TEST_LAMBDA_PROXY_BACKEND = 'test_lambda_apigw_backend'
    TEST_LAMBDA_PROXY_BACKEND_WITH_PATH_PARAM = 'test_lambda_apigw_backend_path_param'
    TEST_LAMBDA_PROXY_BACKEND_ANY_METHOD = 'test_lambda_apigw_backend_any_method'
    TEST_LAMBDA_PROXY_BACKEND_ANY_METHOD_WITH_PATH_PARAM = 'test_lambda_apigw_backend_any_method_path_param'
    TEST_LAMBDA_SQS_HANDLER_NAME = 'lambda_sqs_handler'
    TEST_LAMBDA_AUTHORIZER_HANDLER_NAME = 'lambda_authorizer_handler'
    TEST_API_GATEWAY_ID = 'fugvjdxtri'
    TEST_API_GATEWAY_AUTHORIZER = {
        'name': 'test',
        'type': 'TOKEN',
        'providerARNs': [
            'arn:aws:cognito-idp:us-east-1:123412341234:userpool/us-east-1_123412341'
        ],
        'authType': 'custom',
        'authorizerUri': 'arn:aws:apigateway:us-east-1:lambda:path/2015-03-31/functions/' +
                         'arn:aws:lambda:us-east-1:123456789012:function:myApiAuthorizer/invocations',
        'authorizerCredentials': 'arn:aws:iam::123456789012:role/apigAwsProxyRole',
        'identitySource': 'method.request.header.Authorization',
        'identityValidationExpression': '.*',
        'authorizerResultTtlInSeconds': 300
    }
    TEST_API_GATEWAY_AUTHORIZER_OPS = [
        {
            'op': 'replace',
            'path': '/name',
            'value': 'test1'
        }
    ]
    def test_api_gateway_kinesis_integration(self):