Error - Shop_Product_Abstract __construct() expected $id to be an integer

#0 /justshopit/jonas2.test.comasys.dk/legacy/Modules/Shop/Classes/Product.class.php(687): Shop_Product_Abstract->__construct(NULL)
#1 /justshopit/jonas2.test.comasys.dk/jsit/design/frontend/default/templates/shop/product.phtml(483): Shop_Product->getVariantPricingProduct()
#2 /justshopit/jonas2.test.comasys.dk/Libraries/Akazell/View.class.php(22): require('/justshopit/jon...')
#3 /justshopit/jonas2.test.comasys.dk/Libraries/Akazell/Controller.class.php(226): Akazell_View->render()
#4 /justshopit/jonas2.test.comasys.dk/legacy/Modules/Shop/Classes/Controller.class.php(53): Akazell_Controller->output()
#5 /justshopit/jonas2.test.comasys.dk/Libraries/JS/Router/Akazell.php(262): Shop_Controller->output()
#6 /justshopit/jonas2.test.comasys.dk/Libraries/JS/JS.php(349): JS\Router\Akazell::dispatch('bobcat-mellem')
#7 /var/www/vhosts/jonas2.test.comasys.dk/httpdocs/index.php(105): JS\JS::run('bobcat-mellem')
#8 {main}