NullPointerException deleting a subscription

This may well be just with jira.atlassian.com data - so check for data corruption first.

java.lang.NullPointerException
at com.atlassian.scheduler.OfBizJobStore.removeTrigger(OfBizJobStore.java:300)
at org.quartz.core.QuartzScheduler.unscheduleJob(QuartzScheduler.java:680)
at org.quartz.impl.StdScheduler.unscheduleJob(StdScheduler.java:268)
at com.atlassian.jira.issue.subscription.DefaultSubscriptionManager.deleteSubscription(DefaultSubscriptionManager.java:132)
at com.atlassian.jira.web.action.filter.FilterSubscription.doDelete(FilterSubscription.java:125)

when I try to delete filter at http://jira.atlassian.com/secure/DeleteSubscription.jspa?subId=10000&filterId=10343