ob_end_clean throws error if output buffer is not active

[Schrank]

To test QPS and when calling the test rule (/mageone/test/rule/?Malicious=<script>) a notification is displayed in "community/Mageone/Qps/Model/Observer.php: 161"

ob_end_flush () : ob_end_flush(): failed to delete and flush buffer. No buffer to delete or flush

and then goes to catch and the page is redirected to 404.

I wrote below code on this line instead of ob_end_clean().

if (ob_get_contents ()) {
    ob_end_clean ();
}