NPE deleting entire filter

When I delete this whole filter:

http://jira.atlassian.com/secure/DeleteFilter!default.jspa?filterId=11980

I get the following exception:

java.lang.NullPointerException
at com.atlassian.jira.issue.subscription.DefaultSubscriptionManager.deleteSubscription(DefaultSubscriptionManager.java:132)
at com.atlassian.jira.web.action.filter.ManageFilters.doDelete(ManageFilters.java:82)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)