Cannot delete an issue type when used in a field layout scheme

If I create a field layout scheme, and set it as the "project default" layout in a project, then attempts to delete an issue used in the layout scheme fail:

• javax.servlet.error.message : null<p><small><small><pre>java.lang.NullPointerException at com.atlassian.jira.issue.fields.layout.field.enterprise.EnterpriseFieldLayoutManager.removeSchemeAssociation(EnterpriseFieldLayoutManager.java:327) at com.atlassian.jira.web.action.admin.issuetypes.DeleteIssueType.doExecute(DeleteIssueType.java:157) at webwork.action.ActionSupport.execute(ActionSupport.java:151) at com.atlassian.jira.action.JiraActionSupport.execute(JiraActionSupport.java:46) at webwork.dispatcher.GenericDispatcher.executeAction(GenericDispatcher.java:131) at com.atlassian.jira.web.dispatcher.JiraServletDispatcher.service(JiraServletDispatcher.java:186) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:142) at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:58) at com.atlassian.jira.web.filters.SitemeshExcludePathFilter.doFilter(SitemeshExcludePathFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.SecurityFilter.doFilter(SecurityFilter.java:168) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:181) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132) at com.atlassian.jira.web.filters.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:25) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.jira.web.filters.ActionCleanupDelayFilter.doFilter(ActionCleanupDelayFilter.java:37) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:91) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.jira.web.filters.gzip.GzipFilter.doFilter(GzipFilter.java:72) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:36) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174) at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480) at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995) at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java:193) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:781) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:549) at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:589) at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:666) at java.lang.Thread.run(Thread.java:534) </pre></small></small></p>