RS in CP editor if the page is dropped at the end

RedScreen on node8 9.0.4
2013-09-30 08:57:25,365 [ajp-apr-8008-exec-9] ERROR OLATRuntimeException - OLAT::ERROR ^% N8-E17
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_6_8) AppleWebKit/534.59.10 (KHTML, like Gecko) Version/5.1.9 Safari/534.59.10
*RedScreen*
<dispatchinfo>
<componentinfo>
<compname>cp</compname>
<compclass>org.olat.core.gui.components.tree.MenuTree</compclass>
<extendedinfo>n/a</extendedinfo>
<event>
<class>org.olat.core.gui.components.tree.TreeDropEvent</class>
<command>ctdrop</command>
<tostring>TreeDropEvent:

{cmd:ctdrop, droppedNodeId:11, targetNodeId:6380724dcfde8b706507f7a963990406}

</tostring>
</event>
</componentinfo>
<controllerinfo>
<controllername>org.olat.ims.cp.ui.CPTreeController</controllername>
<controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername>
<controllername>org.olat.core.commons.chiefcontrollers.controller.simple.SimpleBaseController</controllername>
<controllername>org.olat.core.commons.chiefcontrollers.BaseChiefController</controllername>
</controllerinfo>
</dispatchinfo>
>>> stack of 1.cause::org.olat.core.logging.OLATRuntimeException: null
-> at org.olat.core.gui.exception.ExceptionWindowController.<init>(ExceptionWindowController.java:107)
at org.olat.core.gui.exception.MsgFactory.createMessageChiefController(MsgFactory.java:57)
at org.olat.core.gui.exception.MsgFactory.createMessageChiefController(MsgFactory.java:46)
at org.olat.core.gui.components.Window.dispatchRequest(Window.java:508)
at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:226)
at org.olat.core.gui.components.Component.dispatchRequest(Component.java:192)
at org.olat.dispatcher.AuthenticatedDispatcher.execute(AuthenticatedDispatcher.java:227)
at org.olat.core.dispatcher.DispatcherAction.execute(DispatcherAction.java:154)
at org.olat.core.servlets.OLATServlet.doPost(OLATServlet.java:155)
at org.olat.core.servlets.OLATServlet.doGet(OLATServlet.java:128)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
>>> stack of 2.cause::java.lang.NullPointerException: null
-> at org.olat.core.util.tree.TreeHelper.indexOf(TreeHelper.java:89)
at org.olat.ims.cp.ui.CPTreeController.doDrop(CPTreeController.java:430)
at org.olat.ims.cp.ui.CPTreeController.event(CPTreeController.java:359)
at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:195)
at org.olat.core.gui.components.Component$1.run(Component.java:238)
at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
at org.olat.core.gui.components.Component.fireEvent(Component.java:236)
at org.olat.core.gui.components.tree.MenuTree.handleDropped(MenuTree.java:199)
at org.olat.core.gui.components.tree.MenuTree.doDispatchRequest(MenuTree.java:173)
at org.olat.core.gui.components.Component.dispatchRequest(Component.java:192)
at org.olat.core.gui.components.Window.doDispatchToComponent(Window.java:1137)