NPE in reminder of task if the task list was never created

java.lang.NullPointerException
	at org.olat.course.nodes.gta.manager.GTAManagerImpl.getTasks(GTAManagerImpl.java:774)
	at org.olat.course.nodes.gta.rule.AbstractDueDateTaskRuleSPI.getGroupsToRemind(AbstractDueDateTaskRuleSPI.java:212)
	at org.olat.course.nodes.gta.rule.AbstractDueDateTaskRuleSPI.getPeopleToRemind(AbstractDueDateTaskRuleSPI.java:113)
	at org.olat.course.nodes.gta.rule.AbstractDueDateTaskRuleSPI.evaluateRule(AbstractDueDateTaskRuleSPI.java:99)
	at org.olat.course.nodes.gta.rule.AbstractDueDateTaskRuleSPI.evaluate(AbstractDueDateTaskRuleSPI.java:86)
	at org.olat.modules.reminder.manager.ReminderRuleEngine.getIdentities(ReminderRuleEngine.java:168)
	at org.olat.modules.reminder.manager.ReminderRuleEngine.evaluate(ReminderRuleEngine.java:95)
	at org.olat.modules.reminder.manager.ReminderServiceImpl.sendReminder(ReminderServiceImpl.java:234)
	at org.olat.modules.reminder.manager.ReminderServiceImpl.remindAll(ReminderServiceImpl.java:228)
	at org.olat.modules.reminder.manager.ReminderJob.executeWithDB(ReminderJob.java:43)
	at org.olat.core.commons.services.scheduler.JobWithDB.executeInternal(JobWithDB.java:59)
	at org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:114)
	at org.quartz.core.JobRunShell.run(JobRunShell.java:223)
	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:549)