Deprecated functionality: trim(): Passing null to parameter #1 ($string) of type string is deprecated  in /var/www/magento/app/code/local/Amasty/Shopby/Model/Url/Builder.php on line 151

#0 [internal function]: mageCoreErrorHandler()
#1 /var/www/magento/app/code/local/Amasty/Shopby/Model/Url/Builder.php(151): trim()
#2 /var/www/magento/app/code/local/Amasty/Shopby/Model/Url/Builder.php(126): Amasty_Shopby_Model_Url_Builder->excludeParams()
#3 /var/www/magento/app/code/local/Amasty/Shopby/Model/Url/Builder.php(110): Amasty_Shopby_Model_Url_Builder->updateEffectiveQuery()
#4 /var/www/magento/app/code/local/Amasty/Shopby/Model/Observer.php(62): Amasty_Shopby_Model_Url_Builder->getUrl()
#5 /var/www/magento/app/code/local/Amasty/Shopby/Model/Observer.php(19): Amasty_Shopby_Model_Observer->checkRedirectToSeo()
#6 /var/www/magento/app/code/core/Mage/Core/Model/App.php(1441): Amasty_Shopby_Model_Observer->handleCatalogControllerCategoryInitAfter()
#7 /var/www/magento/app/code/core/Mage/Core/Model/App.php(1419): Mage_Core_Model_App->_callObserverMethod()
#8 /var/www/magento/app/Mage.php(509): Mage_Core_Model_App->dispatchEvent()
#9 /var/www/magento/app/code/core/Mage/Catalog/controllers/CategoryController.php(50): Mage::dispatchEvent()
#10 /var/www/magento/app/code/core/Mage/Catalog/controllers/CategoryController.php(119): Mage_Catalog_CategoryController->_initCategory()
#11 /var/www/magento/app/code/core/Mage/Core/Controller/Varien/Action.php(421): Mage_Catalog_CategoryController->viewAction()
#12 /var/www/magento/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(255): Mage_Core_Controller_Varien_Action->dispatch()
#13 /var/www/magento/app/code/core/Mage/Core/Controller/Varien/Front.php(181): Mage_Core_Controller_Varien_Router_Standard->match()
#14 /var/www/magento/app/code/core/Mage/Core/Model/App.php(358): Mage_Core_Controller_Varien_Front->dispatch()
#15 /var/www/magento/app/Mage.php(740): Mage_Core_Model_App->run()
#16 /var/www/magento/index.php(63): Mage::run()
#17 {main}