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.
apig = aws_stack.connect_to_service('apigateway')
        authorizer = apig.create_authorizer(
            restApiId=self.TEST_API_GATEWAY_ID,
            **self.TEST_API_GATEWAY_AUTHORIZER)
        authorizer_id = authorizer.get('id')
        create_result = apig.get_authorizer(
            restApiId=self.TEST_API_GATEWAY_ID,
            authorizerId=authorizer_id)
        # ignor
        del create_result['ResponseMetadata']
        create_expected = clone(self.TEST_API_GATEWAY_AUTHORIZER)
        create_expected['id'] = authorizer_id
        self.assertDictEqual(create_expected, create_result)
        apig.update_authorizer(
            restApiId=self.TEST_API_GATEWAY_ID,
            authorizerId=authorizer_id,
            patchOperations=self.TEST_API_GATEWAY_AUTHORIZER_OPS)
        update_result = apig.get_authorizer(
            restApiId=self.TEST_API_GATEWAY_ID,
            authorizerId=authorizer_id)
        # ignor
        del update_result['ResponseMetadata']
        update_expected = apply_patch(create_expected, self.TEST_API_GATEWAY_AUTHORIZER_OPS)
        self.assertDictEqual(update_expected, update_result)
        apig.delete_authorizer(
            restApiId=self.TEST_API_GATEWAY_ID,
            authorizerId=authorizer_id)
        self.assertRaises(