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
        logs_client = aws_stack.connect_to_service('logs')
        log_group_name = '/aws/lambda/%s' % func_details.name()
        time_str = time.strftime('%Y/%m/%d', time.gmtime(invocation_time))
        log_stream_name = '%s/[$LATEST]%s' % (time_str, short_uid())
        
        log_groups = logs_client.describe_log_groups()['logGroups']
        log_groups = [lg['logGroupName'] for lg in log_groups]
        if log_group_name not in log_groups:
            try:
                logs_client.create_log_group(logGroupName=log_group_name)
            except Exception as e:
                if 'ResourceAlreadyExistsException' in str(e):
                    
                    pass
                else:
                    raise e
        
        logs_client.create_log_stream(logGroupName=log_group_name, logStreamName=log_stream_name)
        
        invocation_time = invocation_time
        finish_time = int(time.time() * 1000)
        log_lines = log_output.split('\n')
        time_diff_per_line = float(finish_time - invocation_time) / float(len(log_lines))
        log_events = []
        for i, line in enumerate(log_lines):
            if not line:
                continue
            
            log_time = invocation_time + float(i) * time_diff_per_line