requestStack not working in Subscriber.php

I am trying to get some form data (user input data) into the subscriber directly, as mentioned in this tutorial by @Shopwarian:

This is the error I am getting.

I have to use the SystemConfig as well so that can not be removed.

How does your service.xml look like?

The issue is resolved now. I did not give the argument for requestStack in the service.xml

that’s what I suspected