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.
LOG.error('Unable to exec: %s %s' % (script, traceback.format_exc()))
        raise e
    finally:
        if lambda_cwd or lambda_env:
            if lambda_cwd:
                os.chdir(previous_cwd)
                sys.path.pop(0)
            if lambda_env:
                os.environ = previous_env
            exec_mutex.release()
    return module_vars[handler_function]
def get_handler_file_from_name(handler_name, runtime=LAMBDA_DEFAULT_RUNTIME):
    
    delimiter = '.'
    if runtime.startswith(LAMBDA_RUNTIME_NODEJS):
        file_ext = '.js'
    elif runtime.startswith(LAMBDA_RUNTIME_GOLANG):
        file_ext = ''
    elif runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE2) or runtime.startswith(LAMBDA_RUNTIME_DOTNETCORE21):
        file_ext = '.dll'
        delimiter = ':'
    elif runtime.startswith(LAMBDA_RUNTIME_RUBY):
        file_ext = '.rb'
    elif runtime.startswith(LAMBDA_RUNTIME_CUSTOM_RUNTIME):
        file_ext = '.sh'
    else:
        handler_name = handler_name.rpartition(delimiter)[0].replace(delimiter, os.path.sep)
        file_ext = '.py'
    return '%s%s' % (handler_name.split(delimiter)[0], file_ext)
def get_handler_function_from_name(handler_name, runtime=LAMBDA_DEFAULT_RUNTIME):