QPool: item list can have null value

2019-01-06 15:43:45,516 [ajp-nio2-8008-exec-222] ERROR OLATRuntimeException - OLAT::ERROR ^%^ N8-E358

https://olat.xyz.ch/auth/QPool/0/QPool/354713600
Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko ^%^ **RedScreen**

<dispatchinfo>
	<componentinfo>
		<compname>ffo_main_item_list</compname>
		<compclass>org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.components.form.flexible.impl.FormEvent</class&gt;
			<command>done</command>
			<tostring>com:done,org.olat.core.gui.components.form.flexible.impl.FormEvent@2f23a1</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.modules.qpool.ui.QuestionListController</controllername>
		<controllername>org.olat.modules.qpool.ui.QuestionPoolMainEditorController</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:589)
   at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:282)
   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:294)
   at org.olat.core.servlets.OpenOLATServlet.doPost(OpenOLATServlet.java:237)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
>>> stack of 2.cause::java.lang.NullPointerException: null
-> at org.olat.modules.qpool.manager.QuestionPoolServiceImpl.lambda$getExportFormatOptions$0(QuestionPoolServiceImpl.java:392)
   at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:174)
   at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
   at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
   at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
   at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
   at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
   at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
   at org.olat.modules.qpool.manager.QuestionPoolServiceImpl.getExportFormatOptions(QuestionPoolServiceImpl.java:398)
   at org.olat.modules.qpool.ui.wizard.ExportTypeController.<init>(ExportTypeController.java:65)
   at org.olat.modules.qpool.ui.wizard.Export_1_TypeStep.getStepController(Export_1_TypeStep.java:58)