500 Internal Server Error

Trying to access array offset on value of type null (2)

#0 /home/oxiprod/public_html/learning/classes/core/Controllers/HomeController.class.php(319): flight\Engine->handleError(2, 'Trying to acces...', '/home/oxiprod/p...', 319)
#1 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/core/Dispatcher.php(224): HomeController::viewSoftwareDownloadsAsset('andor-sdk3-3.15...')
#2 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/core/Dispatcher.php(162): flight\core\Dispatcher::invokeMethod(Array, Array)
#3 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/Engine.php(368): flight\core\Dispatcher::execute(Array, Array)
#4 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/core/Dispatcher.php(219): flight\Engine->_start()
#5 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/core/Dispatcher.php(162): flight\core\Dispatcher::invokeMethod(Array, Array)
#6 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/core/Dispatcher.php(54): flight\core\Dispatcher::execute(Array, Array)
#7 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/Engine.php(98): flight\core\Dispatcher->run('start', Array)
#8 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/core/Dispatcher.php(219): flight\Engine->__call('start', Array)
#9 /home/oxiprod/public_html/learning/classes/vendor/mikecao/flight/flight/Flight.php(97): flight\core\Dispatcher::invokeMethod(Array, Array)
#10 /home/oxiprod/public_html/learning/index.php(7): Flight::__callStatic('start', Array)
#11 {main}