Exception 'Error' with message 'Call to a member function getSubCategory() on null' 

in /home/firko198/blablaprice.com/frontend/controllers/SiteController.php:856

Stack trace:
#0 [internal function]: frontend\controllers\SiteController->actionFilter('915')
#1 /home/firko198/blablaprice.com/vendor/yiisoft/yii2/base/InlineAction.php(57): call_user_func_array(Array, Array)
#2 /home/firko198/blablaprice.com/vendor/yiisoft/yii2/base/Controller.php(156): yii\base\InlineAction->runWithParams(Array)
#3 /home/firko198/blablaprice.com/vendor/yiisoft/yii2/base/Module.php(523): yii\base\Controller->runAction('filter', Array)
#4 /home/firko198/blablaprice.com/vendor/yiisoft/yii2/web/Application.php(102): yii\base\Module->runAction('site/filter', Array)
#5 /home/firko198/blablaprice.com/vendor/yiisoft/yii2/base/Application.php(380): yii\web\Application->handleRequest(Object(yii\web\Request))
#6 /home/firko198/blablaprice.com/frontend/web/index.php(38): yii\base\Application->run()
#7 {main}