Flushing buffer results in Response->write() error

I use a common buffer flushing function:

function buffer_flush(){
    while (ob_get_level() > 0) {
        ob_end_flush();
    }
    flush();
}

and in my view if I use buffer_flush() I don't specify an exit; at the end of the code, the following exception is thrown:

500 Internal Server Error
Argument 1 passed to flight\net\Response::write() must be of the type string, bool given, called in /var/www/vendor/mikecao/flight/flight/Engine.php on line 430 (0)

#0 /var/www/vendor/mikecao/flight/flight/Engine.php(430): flight\net\Response->write()
#1 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(219): flight\Engine->_stop()
#2 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(162): flight\core\Dispatcher::invokeMethod()
#3 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(54): flight\core\Dispatcher::execute()
#4 /var/www/vendor/mikecao/flight/flight/Engine.php(98): flight\core\Dispatcher->run()
#5 /var/www/vendor/mikecao/flight/flight/Engine.php(346): flight\Engine->__call()
#6 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(190): flight\Engine->flight\{closure}()
#7 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(163): flight\core\Dispatcher::callFunction()
#8 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(141): flight\core\Dispatcher::execute()
#9 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(58): flight\core\Dispatcher->filter()
#10 /var/www/vendor/mikecao/flight/flight/Engine.php(98): flight\core\Dispatcher->run()
#11 /var/www/vendor/mikecao/flight/flight/core/Dispatcher.php(219): flight\Engine->__call()
#12 /var/www/vendor/mikecao/flight/flight/Flight.php(97): flight\core\Dispatcher::invokeMethod()
#13 /var/www/index.php(38): Flight::__callStatic()
#14 {main}

Perhaps my buffer flushing is not ideal but it seems like write should be aware that ob_get_clean may return false

flightphp / core

Flushing buffer results in Response->write() error #496