Fix unhandled error case in stream choosing logic
Fix unhandled error case in stream choosing logic

Properly handle the case where the requested PID doesn't
exist or there is simply no video stream.

Signed-off-by: Derek Buitenhuis <aff7d637ede26ea82e5226e01b697996cc52e526@gmail.com>

dwbuiten/d2vsource,dwbuiten/d2vsource