Personalised Chamaedorea Palm Plant

Fatal error: Uncaught ArgumentCountError: Too few arguments to function Mage_Catalog_Model_Resource_Product_Collection::addAttributeToSort(), 0 passed in /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/design/frontend/pnp/plant/template/filterproducts/free_pot.phtml on line 9 and at least 1 expected in /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/code/local/Mage/Catalog/Model/Resource/Product/Collection.php:1548 Stack trace: #0 /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/design/frontend/pnp/plant/template/filterproducts/free_pot.phtml(9): Mage_Catalog_Model_Resource_Product_Collection->addAttributeToSort() #1 /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/code/core/Mage/Core/Block/Template.php(241): include('/home/643624.cl...') #2 /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView() #3 /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/code/core/Mage/Core/Block/Template.php(286): in /home/643624.cloudwaysapps.com/ckfrtcfmvh/public_html/app/code/local/Mage/Catalog/Model/Resource/Product/Collection.php on line 1548