Very strange, the log shows that somthing is telling Minion to close...
Code:
DEBUG 2016-12-27 20:32:15,995 [JavaFX Application Thread] gg.minion.Minion:stop(98): Close called.
DEBUG 2016-12-27 20:32:15,995 [Thread-7] gg.minion.MinionShutdownHook:run(21): Shutdown hook called.
I'm running sierra myself and haven't had any issues.
Could you move or rename your ~/.minion/minion.xml ? Does it load up ok now?