RS in score editing of match interaction

2017-09-04 11:08:14,355 [ajp-nio2-8069-exec-91] ERROR OLATRuntimeException - OLAT::ERROR ^%^ N69-E4 ^%^ org.olat.core.logging 

https://edu.xyz.ch/auth/RepositoryEntry/12222466/Editor/0
Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko ^%^ **RedScreen**

<dispatchinfo>
	<componentinfo>
		<compname>ffo_main_null</compname>
		<compclass>org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.control.Event</class&gt;
			<command>validation ok</command>
			<tostring>com:validation ok,org.olat.core.gui.control.Event@d62b3f02</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.ims.qti21.ui.editor.interactions.MatchScoreController</controllername>
		<controllername>org.olat.ims.qti21.ui.editor.AssessmentItemEditorController</controllername>
		<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: empty String
-> 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.NumberFormatException: empty String
-> at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
   at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
   at java.lang.Double.parseDouble(Double.java:538)
   at org.olat.ims.qti21.ui.editor.interactions.MatchScoreController.formOK(MatchScoreController.java:250)
   at org.olat.core.gui.components.form.flexible.impl.FormBasicController.event(FormBasicController.java:389)
   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.form.flexible.impl.FormWrapperContainer.fireValidation(FormWrapperContainer.java:122)
   at org.olat.core.gui.components.form.flexible.impl.Form.submit(Form.java:479)