6. Attach the spotify-dump.txt ( $HOME/spotify-dump.txt ) from Advanced troubleshooting
7. The daily mix is not crash the client in the other Debian 9 stretch machine. But in the "problem" machine, tried to delete .config/spotify, .cache/spotify, and completely remove Spotify and reinstall, these methods just didn't work.
Update: after upgrade to premium, the client not crash at daily mix anymore. It's just... wired.