panic(cpu 2 caller 0xffffff7f8d19cad5): userspace watchdog timeout: no successful checkins from com.apple.WindowServer in 140 seconds service: com.apple.logd, total successful checkins since wake (7930 seconds ago): 794, last successful checkin: 0 seconds ago service: com.apple.WindowServer, total successful checkins since wake (7930 seconds ago): 780, last successful checkin: 140 seconds ago