Real SQS throws `There should be at least one SendMessageBatchRequestEntry in the request. (Service: AmazonSQS; Status Code: 400; Error Code: AWS.SimpleQueueService.EmptyBatchRequest;` when there is a send batch of zero size.

This would be useful to mimic inside localstack in order to find these bugs earlier.
queue_name = 'queue-{}'.format(short_uid())
        queue_url = self.client.create_queue(QueueName=queue_name)['QueueUrl']
        number_of_messages = 3
        for i in range(number_of_messages):
            self.client.send_message(
                QueueUrl=queue_url,
                MessageBody='hello world. {}'.format(i),
                DelaySeconds=0
            )
        messages = {}
        for i in range(number_of_messages):
            rs = self.client.receive_message(QueueUrl=queue_url)
            m = rs['Messages'][0]
            messages[m['MessageId']] = m['Body']
        self.assertEqual(len(messages.keys()), number_of_messages)
        
        self.client.delete_queue(QueueUrl=queue_url)
    def test_lambda_invoked_by_sqs_message_with_delay_seconds(self):
        function_name = 'lambda_func-{}'.format(short_uid())
        queue_name = 'queue-{}'.format(short_uid())
        delay_time = 6
        queue_url = self.client.create_queue(QueueName=queue_name)['QueueUrl']
        queue_arn = aws_stack.sqs_queue_arn(queue_name)
        testutil.create_lambda_function(
            handler_file=TEST_LAMBDA_ECHO_FILE,
            func_name=function_name,
            runtime=LAMBDA_RUNTIME_PYTHON36
        )
        lambda_client = aws_stack.connect_to_service('lambda')