Fatal error: Uncaught Symfony\Component\Debug\Exception\FatalThrowableError: Type error: substr() expects parameter 1 to be string, null given in /home/upio/mountair.com/staging/releases/20210421093529/src/FrontendBundle/EventListener/LangExecuteListener.php:41 Stack trace: #0 /home/upio/mountair.com/staging/releases/20210421093529/src/FrontendBundle/EventListener/LangExecuteListener.php(41): substr(NULL, 0, 2) #1 /home/upio/mountair.com/staging/releases/20210421093529/vendor/symfony/symfony/src/Symfony/Component/EventDispatcher/EventDispatcher.php(214): Mountair\FrontendBundle\EventListener\LangExecuteListener->onKernelRequest(Object(Symfony\Component\HttpKernel\Event\GetResponseEvent), 'kernel.request', Object(Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher)) #2 /home/upio/mountair.com/staging/releases/20210421093529/vendor/symfony/symfony/src/Symfony/Component/EventDispatcher/EventDispatcher.php(44): Symfony\Component\EventDispatcher\EventDispatcher->doDispatch(Array, 'kernel.request', Object(Symfony\Co in /home/upio/mountair.com/staging/releases/20210421093529/src/FrontendBundle/EventListener/LangExecuteListener.php on line 41