If you dont know what is that, can you please pass these details to us:
Trying to get property of non-object
#0 /home/firspark/public_html/app/controller/sales.php(40): snail_error(8, 'Trying to get p...', '/home/firspark/...', 40, Array)
#1 /home/firspark/public_html/snail/snail/router.php(53): App_Controller_Sales->show(Array)
#2 /home/firspark/public_html/snail/snail/router.php(44): core_snail_router->controller('app_controller_...', Object(stdClass), Array)
#3 /home/firspark/public_html/snail/snail/snail.php(6): core_snail_router->__construct()
#4 /home/firspark/public_html/snail/index.php(21): Core_Snail_Snail->__construct()
#5 /home/firspark/public_html/index.php(5): include('/home/firspark/...')
#6 {main}