Reported from user that when exporting aggregation reports from GUI, sometimes, QB crashes and throws this error:

Root cause:
 
java.lang.NullPointerException
                at com.pmease.quickbuild.plugin.report.engine.renderer.aggregation.DefaultAggregationPanel$ExportMenuItem$2.load(DefaultAggregationPanel.java:245)
                at com.pmease.quickbuild.plugin.report.engine.renderer.aggregation.DefaultAggregationPanel$ExportMenuItem$2.load(DefaultAggregationPanel.java:221)
                at org.apache.wicket.model.LoadableDetachableModel.getObject(LoadableDetachableModel.java:119)
                at org.apache.wicket.Component.getDefaultModelObject(Component.java:1650)
                at org.apache.wicket.markup.html.link.Link.getModelObject(Link.java:447)
                at org.apache.wicket.markup.html.link.DownloadLink.onClick(DownloadLink.java:139)
                at org.apache.wicket.markup.html.link.Link.onLinkClicked(Link.java:187)
                at java.lang.reflect.Method.invoke(Method.java:606)
                at org.apache.wicket.RequestListenerInterface.internalInvoke(RequestListenerInterface.java:272)
                at org.apache.wicket.RequestListenerInterface.invoke(RequestListenerInterface.java:220)
                at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.invokeListener(ListenerInterfaceRequestHandler.java:179)
                at org.apache.wicket.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:165)
                at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:719)
                at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:63)
                at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:210)
                at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:253)
                at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:162)
                at org.apache.wicket.protocol.http.WicketServlet.doGet(WicketServlet.java:137)
                at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
                at com.pmease.quickbuild.web.MainServlet.service(MainServlet.java:133)
                at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
                at org.eclipse.equinox.http.helper.FilterServletAdaptor$FilterChainImpl.doFilter(FilterServletAdaptor.java:56)
                at org.eclipse.jetty.servlets.UserAgentFilter.doFilter(UserAgentFilter.java:82)
                at org.eclipse.jetty.servlets.GzipFilter.doFilter(GzipFilter.java:243)
                at org.eclipse.equinox.http.helper.FilterServletAdaptor.service(FilterServletAdaptor.java:37)
                at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:669)
                at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1336)
                at com.pmease.quickbuild.Quickbuild$DisableTraceFilter.doFilter(Quickbuild.java:1057)
                at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1307)
                at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:453)
                at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:229)
                at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1072)
                at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:382)
                at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:193)
                at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1006)
                at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
                at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154)
                at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
                at org.eclipse.jetty.server.Server.handle(Server.java:365)
                at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:485)
                at org.eclipse.jetty.server.BlockingHttpConnection.handleRequest(BlockingHttpConnection.java:53)
                at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:926)
                at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:988)
                at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:635)
                at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
                at org.eclipse.jetty.server.BlockingHttpConnection.handle(BlockingHttpConnection.java:72)
                at org.eclipse.jetty.server.bio.SocketConnector$ConnectorEndPoint.run(SocketConnector.java:264)
                at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
                at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
                at java.lang.Thread.run(Thread.java:724)