RS in QTI 2.1 editor if user want to delete "nothing"

2017-04-05 15:10:29,113 [ajp-nio2-8060-exec-1] ERROR OLATRuntimeException - OLAT::ERROR ^%^ N60-E1 ^%^ org.olat.core.logging

https://xyz.openolat.com/auth/RepositoryEntry/15073284/Editor/0
Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; LCJB; rv:11.0) like Gecko
**RedScreen**
<dispatchinfo>
	<componentinfo>
		<compname>tools.delete</compname>
		<compclass>org.olat.core.gui.components.link.Link</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.control.Event</class&gt;
			<command>tools.delete</command>
			<tostring>com:tools.delete,org.olat.core.gui.control.Event@604ba53d</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.ims.qti21.ui.editor.AssessmentTestComposerController</controllername>
		<controllername>org.olat.ims.qti21.ui.QTI21RuntimeController</controllername>
		<controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername>
	</controllerinfo>
</dispatchinfo>

>>> stack of 1.cause::org.olat.core.logging.OLATRuntimeException: null
-> at org.olat.core.gui.exception.ExceptionWindowController.<init>(ExceptionWindowController.java:116)
   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:549)
   at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:242)
   at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193)
   at org.olat.dispatcher.AuthenticatedDispatcher.processValidDispatchURI(AuthenticatedDispatcher.java:273)
   at org.olat.dispatcher.AuthenticatedDispatcher.execute(AuthenticatedDispatcher.java:190)
   at org.olat.core.servlets.OpenOLATServlet.executeUserRequest(OpenOLATServlet.java:292)
   at org.olat.core.servlets.OpenOLATServlet.doPost(OpenOLATServlet.java:235)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
>>> stack of 2.cause::java.lang.NullPointerException: null
-> at org.olat.ims.qti21.ui.editor.AssessmentTestComposerController.doConfirmDelete(AssessmentTestComposerController.java:1198)
   at org.olat.ims.qti21.ui.editor.AssessmentTestComposerController.event(AssessmentTestComposerController.java:490)
   at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:202)
   at org.olat.core.gui.components.AbstractComponent$1.run(AbstractComponent.java:240)
   at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
   at org.olat.core.gui.components.AbstractComponent.fireEvent(AbstractComponent.java:238)
   at org.olat.core.gui.components.link.Link.dispatch(Link.java:199)
   at org.olat.core.gui.components.link.Link.doDispatchRequest(Link.java:186)
   at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193)
   at org.olat.core.gui.components.Window.doDispatchToComponent(Window.java:1143)
   at org.olat.core.gui.components.Window.dispatchRequest(Window.java:358)