Seems to crash on the multiselect attribute that the badge rule used.
[05-Apr-2023 07:54:04 UTC] PHP Fatal error: Uncaught Error: Call to a member function getBackend() on bool in /public_html/app/code/core/Mage/Catalog/Model/Resource/Product/Collection.php:855
Stack trace:
#0 /public_html/app/code/community/CustomGento/ProductBadges/Model/Rule/Condition/Product/BaseCondition.php(78): Mage_Catalog_Model_Resource_Product_Collection->getAllAttributeValues()
#1 /public_html/app/code/core/Mage/CatalogRule/Model/Rule/Condition/Combine.php(63): CustomGento_ProductBadges_Model_Rule_Condition_Product_BaseCondition->collectValidatedAttributes()
#2 /public_html/app/code/community/CustomGento/ProductBadges/Model/BadgeConfig.php(79): Mage_CatalogRule_Model_Rule_Condition_Combine->collectValidatedAttributes()
#3 /public_html/app/code/community/CustomGento/ProductBadges/Model/Scanner/ProductBadges.php(68): CustomGento_ProductBadges_Model_BadgeConfig->getMatchingProductIds()
#4 /public_html/app/code/community/CustomGento/ProductBadges/Model/Resource/Indexer/ProductBadges.php(112): CustomGento_ProductBadges_Model_Scanner_ProductBadges->fetchBadges()
#5 /public_html/app/code/community/CustomGento/ProductBadges/Model/Resource/Indexer/ProductBadges.php(91): CustomGento_ProductBadges_Model_Resource_Indexer_ProductBadges->rebuild()
#6 /public_html/app/code/community/CustomGento/ProductBadges/Model/Resource/Indexer/ProductBadges.php(63): CustomGento_ProductBadges_Model_Resource_Indexer_ProductBadges->rebuild()
#7 /public_html/app/code/core/Mage/Index/Model/Indexer/Abstract.php(145): CustomGento_ProductBadges_Model_Resource_Indexer_ProductBadges->reindexAll()
#8 /public_html/app/code/core/Mage/Index/Model/Process.php(207): Mage_Index_Model_Indexer_Abstract->reindexAll()
#9 /public_html/app/code/core/Mage/Index/Model/Process.php(255): Mage_Index_Model_Process->reindexAll()
#10 /public_html/app/code/core/Mage/Index/controllers/Adminhtml/ProcessController.php(189): Mage_Index_Model_Process->reindexEverything()
#11 /public_html/app/code/core/Mage/Core/Controller/Varien/Action.php(428): Mage_Index_Adminhtml_ProcessController->massReindexAction()
#12 /public_html/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(262): Mage_Core_Controller_Varien_Action->dispatch()
#13 /public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(188): Mage_Core_Controller_Varien_Router_Standard->match()
#14 /public_html/app/code/core/Mage/Core/Model/App.php(371): Mage_Core_Controller_Varien_Front->dispatch()
#15 /public_html/app/Mage.php(735): Mage_Core_Model_App->run()
#16 /public_html/index.php(165): Mage::run()
#17 {main}
thrown in /public_html/app/code/core/Mage/Catalog/Model/Resource/Product/Collection.php on line 855