I have update to Linux 5.2 kernel from unstable and the problem is solved !
I played several days without any crash. I think it would be nice to backport the fix into Debian 10 standard kernel as otherwise it not possible to play 3D games with AMD cards without OS hang. I'm available to test any kernel build for Debian 10 if necessary. Or put a notice so that people know they should install the linux 5.2 backported kernel once available.
