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.
return ContainerInfo(container_name, entry_point)
    def destroy_docker_container(self, func_arn):
        """
        Stops and/or removes a docker container for a specific lambda function ARN.
        :param func_arn: The ARN of the lambda function.
        :return: None
        """
        with self.docker_container_lock:
            status = self.get_docker_container_status(func_arn)
            docker_cmd = self._docker_cmd()
            
            container_name = self.get_container_name(func_arn)
            if status == 1:
                LOG.debug('Stopping container: %s' % container_name)
                cmd = (
                    '%s stop -t0 %s'
                ) % (docker_cmd, container_name)
                LOG.debug(cmd)
                run(cmd, asynchronous=False, stderr=subprocess.PIPE, outfile=subprocess.PIPE)
                status = self.get_docker_container_status(func_arn)
            if status == -1:
                LOG.debug('Removing container: %s' % container_name)
                cmd = (
                    '%s rm %s'
                ) % (docker_cmd, container_name)
                LOG.debug(cmd)
                run(cmd, asynchronous=False, stderr=subprocess.PIPE, outfile=subprocess.PIPE)
    def get_all_container_names(self):
        """
        Returns a list of container names for lambda containers.