T&Q: Unable to export the scores of an online exam with the answer point value as zero.

User is unable to export the scores from the class. when we click on export button, it goes to assessment list first then next time its get crash.
The issue occurred when the staff created an online exam with the answer point value as zero.

Error:
org.sakaiproject.portal.api.PortalHandlerException: org.sakaiproject.tool.api.ToolException: javax.servlet.ServletException: /jsf/evaluation/exportResponses.jsp(136,0) '#{exportResponses.exportExcel}' java.lang.NumberFormatException
at org.sakaiproject.portal.charon.handlers.ToolHandler.doPost(ToolHandler.java:73)
caused by: org.sakaiproject.tool.api.ToolException: javax.servlet.ServletException: /jsf/evaluation/exportResponses.jsp(136,0) '#{exportResponses.exportExcel}' java.lang.NumberFormatException
at org.sakaiproject.portal.charon.SkinnableCharonPortal.forwardTool(SkinnableCharonPortal.java:1494)
caused by: javax.servlet.ServletException: /jsf/evaluation/exportResponses.jsp(136,0) '#{exportResponses.exportExcel}' java.lang.NumberFormatException
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
caused by: org.apache.jasper.el.JspELException: /jsf/evaluation/exportResponses.jsp(136,0) '#{exportResponses.exportExcel}' java.lang.NumberFormatException
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:148)
caused by: java.lang.NumberFormatException
at java.math.BigDecimal.<init>(BigDecimal.java:497)
at java.math.BigDecimal.<init>(BigDecimal.java:383)
at java.math.BigDecimal.<init>(BigDecimal.java:809)
at java.math.BigDecimal.valueOf(BigDecimal.java:1277)
at org.sakaiproject.tool.assessment.ui.listener.evaluation.HistogramListener.roundTheDecimal(HistogramListener.java:3181)
at org.sakaiproject.tool.assessment.ui.listener.evaluation.HistogramListener.doScoreStatistics(HistogramListener.java:2296)
at org.sakaiproject.tool.assessment.ui.listener.evaluation.HistogramListener.determineResults(HistogramListener.java:808)
at org.sakaiproject.tool.assessment.ui.listener.evaluation.HistogramListener.histogramScores(HistogramListener.java:475)
at org.sakaiproject.tool.assessment.ui.listener.evaluation.HistogramListener.getDetailedStatisticsSpreadsheetData(HistogramListener.java:2951)
at org.sakaiproject.tool.assessment.ui.bean.evaluation.ExportResponsesBean.getSpreadsheetData(ExportResponsesBean.java:152)
at org.sakaiproject.tool.assessment.ui.bean.evaluation.ExportResponsesBean.exportExcel(ExportResponsesBean.java:143)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.el.parser.AstValue.invoke(AstValue.java:247)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:267)
at org.apache.jasper.el.JspMethodExpression.invoke(JspMethodExpression.java:74)
at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:148)
at javax.faces.event.ActionEvent.processListener(ActionEvent.java:96)
at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:839)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:870)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1418)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:82)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:201)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:670)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:426)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:716)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:466)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:391)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:318)
at org.sakaiproject.jsf.util.SamigoJsfTool.dispatch(SamigoJsfTool.java:360)
at org.sakaiproject.jsf2.util.JsfTool.doPost(JsfTool.java:250)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:716)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:466)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:358)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:318)
at org.sakaiproject.tool.impl.ActiveToolComponent$MyActiveTool.forward(ActiveToolComponent.java:508)
at org.sakaiproject.portal.charon.SkinnableCharonPortal.forwardTool(SkinnableCharonPortal.java:1494)
at org.sakaiproject.portal.charon.handlers.ToolHandler.doTool(ToolHandler.java:200)
at org.sakaiproject.portal.charon.handlers.ToolHandler.doGet(ToolHandler.java:96)
at org.sakaiproject.portal.charon.handlers.ToolHandler.doPost(ToolHandler.java:73)
at org.sakaiproject.portal.charon.SkinnableCharonPortal.doPost(SkinnableCharonPortal.java:1173)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:475)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:455)
at org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:177)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:94)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:80)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:620)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:502)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1152)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1539)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1495)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)