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 self.versions.get(version)
    def max_version(self):
        versions = [int(key) for key in self.versions.keys() if key != '$LATEST']
        return versions and max(versions) or 0
    def name(self):
        
        return self.id.split(':')[6]
    def arn(self):
        return self.id
    def function(self, qualifier=None):
        return self.versions.get(self.get_qualifier_version(qualifier)).get('Function')
    def get_qualifier_version(self, qualifier=None):
        if not qualifier:
            qualifier = '$LATEST'
        return qualifier if qualifier in self.versions else \
            self.aliases.get(qualifier).get('FunctionVersion')
    def qualifier_exists(self, qualifier):
        return qualifier in self.aliases or qualifier in self.versions
    def __str__(self):
        return '<%s:%s>' % (self.__class__.__name__, self.name())
class DynamoDB(Component):
    def __init__(self, id, env=None):
        super(DynamoDB, self).__init__(id, env=env)
        self.count = -1
        self.bytes = -1
    def name(self):
        return self.id.split(':table/')[-1]
class DynamoDBStream(Component):