Here are the docs for media.hasSource():
https://docs.coronalabs.com/api/library/media/hasSource.html
At the bottom of the page, there is a sample code for requesting camera access. When I run exactly that code on a Samsung A20 (Android 9) I get this error:
Aug 21 12:26:00.168 SM-A202F: REQUEST_PERMISSIONS Action.
Aug 21 12:26:11.486 SM-A202F: REQUEST_PERMISSIONS Action.
Aug 21 12:26:18.021 SM-A202F: Execute the lua listener task
Aug 21 12:26:18.021 SM-A202F: ERROR: CoronaActivity.DefaultRequestPermissiosnResultHandler.forwardRequestPermissionsResultToLua():Cannot forward results to Lua as no registry ID was found showbox!
Permission is asked twice. First time for access to the camera (which is correct), and second time for the media library (strange, since I ask for permission only for camera). It is at that second occasion that the error is thrown.
Is this a bug in Corona or are the docs missing something?