NPE in treenode

This seems to happen when performing operations on documents in the "state" folder.

26.10.2009 11:28:05 ERROR [org.hippoecm.frontend.plugins.standards.FolderTreeNode.getChildCount():87] d996d857-27a6-4666-8bcc-b0f4ab90479d: the item does not exist anymore
26.10.2009 11:28:05 ERROR [org.hippoecm.frontend.model.tree.JcrTreeNode.ensureChildrenLoaded():174] d996d857-27a6-4666-8bcc-b0f4ab90479d: the item does not exist anymore
26.10.2009 11:28:05 ERROR [org.apache.wicket.RequestCycle.logRuntimeException():1437] Exception in rendering component: [MarkupContainer [Component id = link]]
org.apache.wicket.WicketRuntimeException: Exception in rendering component: [MarkupContainer [Component id = link]]
at org.apache.wicket.Component.renderComponent(Component.java:2519)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1401)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.hippoecm.frontend.wicket1985.AbstractTree$TreeItem.onRender(AbstractTree.java:211)
at org.apache.wicket.Component.render(Component.java:2317)
at org.hippoecm.frontend.wicket1985.AbstractTree$TreeItemContainer$1.visitItem(AbstractTree.java:374)
at org.hippoecm.frontend.wicket1985.AbstractTree.visitItemAndChildren(AbstractTree.java:1485)
at org.hippoecm.frontend.wicket1985.AbstractTree.visitItemChildren(AbstractTree.java:1504)
at org.hippoecm.frontend.wicket1985.AbstractTree.visitItemAndChildren(AbstractTree.java:1486)
at org.hippoecm.frontend.wicket1985.AbstractTree.visitItemChildren(AbstractTree.java:1504)
at org.hippoecm.frontend.wicket1985.AbstractTree.visitItemAndChildren(AbstractTree.java:1486)
at org.hippoecm.frontend.wicket1985.AbstractTree.access$500(AbstractTree.java:62)
at org.hippoecm.frontend.wicket1985.AbstractTree$TreeItemContainer.onRender(AbstractTree.java:381)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:639)
at org.apache.wicket.markup.html.panel.Panel.onComponentTagBody(Panel.java:112)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:639)
at org.apache.wicket.markup.html.panel.Panel.onComponentTagBody(Panel.java:112)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1401)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.markup.html.list.ListView.renderItem(ListView.java:634)
at org.apache.wicket.markup.html.list.ListView.renderChild(ListView.java:622)
at org.apache.wicket.markup.repeater.AbstractRepeater.onRender(AbstractRepeater.java:100)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:639)
at org.apache.wicket.markup.html.panel.Panel.onComponentTagBody(Panel.java:112)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:639)
at org.apache.wicket.markup.html.panel.Panel.onComponentTagBody(Panel.java:112)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.Component.renderComponent(Component.java:2420)
at org.apache.wicket.ajax.AjaxRequestTarget.respondComponent(AjaxRequestTarget.java:785)
at org.apache.wicket.ajax.AjaxRequestTarget.respondComponents(AjaxRequestTarget.java:662)
at org.apache.wicket.ajax.AjaxRequestTarget.respond(AjaxRequestTarget.java:577)
at org.apache.wicket.request.AbstractRequestCycleProcessor.respond(AbstractRequestCycleProcessor.java:104)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1181)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1252)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1353)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:493)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:355)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:200)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1115)
at org.hippoecm.frontend.plugins.login.ConcurrentLoginFilter.doFilter(ConcurrentLoginFilter.java:54)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1115)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:361)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:534)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:864)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:533)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:207)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:403)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:522)
Caused by: java.lang.NullPointerException
at org.hippoecm.frontend.model.tree.JcrTreeNode.getChildAt(JcrTreeNode.java:89)
at org.hippoecm.frontend.wicket1985.DefaultAbstractTree.isNodeLast(DefaultAbstractTree.java:730)
at org.hippoecm.frontend.wicket1985.DefaultAbstractTree.access$000(DefaultAbstractTree.java:62)
at org.hippoecm.frontend.wicket1985.DefaultAbstractTree$2.onComponentTag(DefaultAbstractTree.java:386)
at org.apache.wicket.Component.renderComponent(Component.java:2451)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1411)
at org.apache.wicket.Component.render(Component.java:2317)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1297)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1476)
at org.apache.wicket.markup.html.link.AbstractLink.onComponentTagBody(AbstractLink.java:165)
at org.apache.wicket.Component.renderComponent(Component.java:2480)
... 86 more