[Building Sakai] Lesson Builder null pointer exception when deleting

[Diego del Blanco Orobitg]

Hi all:

I've this fail in Leson Builder when deleting the last subpage in a Page...
only sometimes :( but a lot of sometimes :), Anyway I've not been able to
find a reason for this "sometimes" not sure when it happens and when it
doesn't happen.

I have sakai 2.9.1 (I've in mind migrate to 2.9.3 soon) and as I've touched
some code (not the code where it fails, I'd like to know if someone has
this error too and if there is a patch (I've not found anything in Jira... )

As said, to reproduce it, if you have a page with some subpages , all of
them as next page and as buttom, when you delete the last one (entering in
the previous one, editing the button with the lik to the next one, and
deleting) sometimes I have this exception.


Fatal internal error handling request:
Target exception of class java.lang.NullPointerException
Successive lines until stack trace show causes progressing to exception
site:

java.lang.NullPointerException
at
org.sakaiproject.lessonbuildertool.tool.beans.SimplePageBean.addPrevLink(SimplePageBean.java:1357)
at
org.sakaiproject.lessonbuildertool.tool.producers.ShowPageProducer.fillComponents(ShowPageProducer.java:827)
 at
uk.org.ponder.rsf.view.support.ViewCollector.fillComponents(ViewCollector.java:56)
at
uk.org.ponder.rsf.view.support.LayoutCollector.fillComponents(LayoutCollector.java:68)
 at sun.reflect.GeneratedMethodAccessor2760.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
at
org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
 at
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:198)
at com.sun.proxy.$Proxy99.fillComponents(Unknown Source)
 at
uk.org.ponder.rsf.view.support.ViewGenerator.generateView(ViewGenerator.java:53)
at
uk.org.ponder.rsf.processor.support.RSFRenderHandler$1.run(RSFRenderHandler.java:79)
 at
uk.org.ponder.rsf.processor.support.RequestInvoker$1.run(RequestInvoker.java:46)
at
uk.org.ponder.util.CollectingRunnableInvoker$1.run(CollectingRunnableInvoker.java:25)
 at
uk.org.ponder.rsf.flow.support.BasicScopedAlterationWrapper.invokeRunnable(BasicScopedAlterationWrapper.java:59)
at
uk.org.ponder.rsf.flow.support.BasicScopedAlterationWrapper$$FastClassByCGLIB$$84f89202.invoke(<generated>)
 at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at
org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:628)
 at
uk.org.ponder.rsf.flow.support.BasicScopedAlterationWrapper$$EnhancerByCGLIB$$715b903c.invokeRunnable(<generated>)
at
uk.org.ponder.rsf.flow.support.BasicScopedAlterationWrapper$$FastClassByCGLIB$$84f89202.invoke(<generated>)
 at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at
org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:628)
 at
uk.org.ponder.rsf.flow.support.BasicScopedAlterationWrapper$$EnhancerByCGLIB$$715b903c.invokeRunnable(<generated>)
at
uk.org.ponder.util.CollectingRunnableInvoker$1.run(CollectingRunnableInvoker.java:29)
 at
uk.org.ponder.util.CollectingRunnableInvoker.invokeWrappers(CollectingRunnableInvoker.java:22)
at
uk.org.ponder.util.CollectingRunnableInvoker.invokeRunnable(CollectingRunnableInvoker.java:14)
 at
uk.org.ponder.rsf.processor.support.RequestInvoker.invokeRunnable(RequestInvoker.java:39)
at
uk.org.ponder.rsf.processor.support.RSFRenderHandler.handle(RSFRenderHandler.java:75)
 at
uk.org.ponder.rsf.processor.support.RSFRenderHandler$$FastClassByCGLIB$$5bda3a3d.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
 at
org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:628)
at
uk.org.ponder.rsf.processor.support.RSFRenderHandler$$EnhancerByCGLIB$$5de8c3b7.handle(<generated>)
 at
uk.org.ponder.rsf.processor.support.RenderHandlerBracketer.handle(RenderHandlerBracketer.java:82)
at
uk.org.ponder.rsf.processor.support.RenderHandlerBracketer$$FastClassByCGLIB$$3055fa0f.invoke(<generated>)
 at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at
org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:628)
 at
uk.org.ponder.rsf.processor.support.RenderHandlerBracketer$$EnhancerByCGLIB$$2b7e4b09.handle(<generated>)
at
uk.org.ponder.rsf.processor.support.RootHandlerBeanBase.handleGet(RootHandlerBeanBase.java:97)
 at
uk.org.ponder.rsf.processor.support.RootHandlerBeanBase.handle(RootHandlerBeanBase.java:79)
at sun.reflect.GeneratedMethodAccessor2587.invoke(Unknown Source)
 at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
 at
uk.org.ponder.reflect.JDKReflectiveCache.invokeMethod(JDKReflectiveCache.java:23)
at
uk.org.ponder.reflect.JDKReflectiveCache.invokeMethod(JDKReflectiveCache.java:17)
 at
uk.org.ponder.reflect.JDKReflectiveCache.invokeMethod(JDKReflectiveCache.java:77)
at
uk.org.ponder.rsac.support.RSACBeanLocatorImpl.createBean(RSACBeanLocatorImpl.java:553)
 at
uk.org.ponder.rsac.support.RSACBeanLocatorImpl.access$000(RSACBeanLocatorImpl.java:75)
at
uk.org.ponder.rsac.support.RSACBeanLocatorImpl$1.run(RSACBeanLocatorImpl.java:449)
 at
uk.org.ponder.rsac.RSACErrorBridge.invokeRunnable(RSACErrorBridge.java:38)
at
uk.org.ponder.rsac.support.RSACBeanLocatorImpl.createBean(RSACBeanLocatorImpl.java:447)
 at
uk.org.ponder.rsac.support.RSACBeanLocatorImpl.getLocalBean(RSACBeanLocatorImpl.java:348)
at
uk.org.ponder.rsac.support.RSACBeanLocatorImpl.getBean(RSACBeanLocatorImpl.java:379)
 at
uk.org.ponder.rsac.support.PerRequestInfo$1.locateBean(PerRequestInfo.java:49)
at
uk.ac.cam.caret.sakai.rsf.servlet.ReasonableSakaiServlet.service(ReasonableSakaiServlet.java:65)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
 at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:634)
 at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
 at
org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:749)
at
org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:487)
 at
org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:379)
at
org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:339)
 at
org.sakaiproject.tool.impl.ActiveToolComponent$MyActiveTool.forward(ActiveToolComponent.java:508)
at
org.sakaiproject.portal.charon.SkinnableCharonPortal.forwardTool(SkinnableCharonPortal.java:1615)
 at
org.sakaiproject.portal.charon.handlers.ToolHandler.doTool(ToolHandler.java:223)
at
org.sakaiproject.portal.charon.handlers.ToolHandler.doGet(ToolHandler.java:98)
 at
org.sakaiproject.portal.charon.SkinnableCharonPortal.doGet(SkinnableCharonPortal.java:903)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
 at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:695)
 at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
 at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
 at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
 at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
 at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
 at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:200)
at
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
 at
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
 at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:662)

-- 
Diego del Blanco Orobitg
Tutordemia IT & Training Manager
Apereo LATAM Representative
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