Greetings from ShepHertz!!!
As your getting ConcurrentModificationException in your android application that can be because of below reason.
In AppWarp you need to add callback listeners to get response form SDK API's. But there may be a case in your android application either you are removing these callback listeners in some thread. This can be a reason you are getting such exception. You can remove such code from the application.
Let me know if it helps, if problem still persists please share the code in more details son that we can trace the exact problem you are facing.
Thanks & Regards