RS if a backup file is missing in the list of versions

2016-04-04 15:21:14,273 [ajp-nio2-8008-exec-77] ERROR OLATRuntimeException - OLAT::ERROR ^%^ N8-E130
https://olat.xyz.ch/auth/RepositoryEntry/243957765/CourseNode/85217548864103/path%3D~~/0

Mozilla/5.0 (Windows NT 6.1; Trident/7.0; rv:11.0) like Gecko ^%^ **RedScreen**

<dispatchinfo>
	<componentinfo>
		<compname>link_0</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>link_0</command>
			<tostring>com:link_0,org.olat.core.gui.control.Event@be46a54a</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.core.gui.control.generic.modal.DialogBoxController</controllername>
		<controllername>org.olat.core.commons.modules.bc.version.RevisionListController</controllername>
		<controllername>org.olat.core.commons.modules.bc.FileUploadController</controllername>
		<controllername>org.olat.core.commons.modules.bc.commands.CmdUpload</controllername>
		<controllername>org.olat.core.commons.modules.bc.FolderRunController</controllername>
		<controllername>org.olat.course.nodes.bc.BCCourseNodeRunController</controllername>
		<controllername>org.olat.course.run.RunMainController</controllername>
		<controllername>org.olat.course.run.CourseRuntimeController</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:536)
   at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:234)
   at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193)
   at org.olat.dispatcher.AuthenticatedDispatcher.processValidDispatchURI(AuthenticatedDispatcher.java:298)
   at org.olat.dispatcher.AuthenticatedDispatcher.execute(AuthenticatedDispatcher.java:216)
   at org.olat.core.servlets.OpenOLATServlet.executeUserRequest(OpenOLATServlet.java:289)
   at org.olat.core.servlets.OpenOLATServlet.doPost(OpenOLATServlet.java:232)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
>>> stack of 2.cause::java.lang.NullPointerException: null
-> at org.olat.core.util.vfs.version.VersionsFileManager.deleteRevisions(VersionsFileManager.java:417)
   at org.olat.core.util.vfs.version.VersionsFileImpl.delete(VersionsFileImpl.java:94)
   at org.olat.core.commons.modules.bc.version.RevisionListController.event(RevisionListController.java:265)
   at org.olat.core.gui.control.DefaultController$1.run(DefaultController.java:246)
   at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
   at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:243)
   at org.olat.core.gui.control.DefaultController.fireEvent(DefaultController.java:190)
   at org.olat.core.gui.control.generic.modal.DialogBoxController.event(DialogBoxController.java:205)
   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)