1. Aug/31 19:06:58 [ERROR] [http-nio-0.0.0.0-9080-exec-2] controller.AbstractAjaxController [[]] (AbstractAjaxController.java:166) - Unhandled exception
2. java.lang.NullPointerException
3.     at java.util.TreeMap.compare(TreeMap.java:1294) ~[?:1.8.0_131]
4.     at java.util.TreeMap.put(TreeMap.java:538) ~[?:1.8.0_131]
5.     at java.util.TreeSet.add(TreeSet.java:255) ~[?:1.8.0_131]
6.     at java.util.AbstractCollection.addAll(AbstractCollection.java:344) ~[?:1.8.0_131]
7.     at java.util.TreeSet.addAll(TreeSet.java:312) ~[?:1.8.0_131]
8.     at java.util.TreeSet.<init>(TreeSet.java:160) ~[?:1.8.0_131]
9.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.getFirstCommonProgram(AssignmentFacadeService.java:2605) ~[AssignmentFacadeService.class:?]
10.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.addProgramMapByClassId(AssignmentFacadeService.java:2525) ~[AssignmentFacadeService.class:?]
11.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.getAssociatedProgramsForAssignment(AssignmentFacadeService.java:2509) ~[AssignmentFacadeService.class:?]
12.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.createEditAssignment(AssignmentFacadeService.java:1633) ~[AssignmentFacadeService.class:?]
13.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.createAssignment(AssignmentFacadeService.java:1156) ~[AssignmentFacadeService.class:?]
14.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.createAssignment(AssignmentFacadeService.java:1117) ~[AssignmentFacadeService.class:?]
15.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService.createAssignment(AssignmentFacadeService.java:1095) ~[AssignmentFacadeService.class:?]
16.     at com.pearson.ltg.ole.service.assignment.AssignmentFacadeService$$FastClassBySpringCGLIB$$e74e88ca.invoke(<generated>) ~[spring-core-4.1.7.RELEASE.jar:?]
17.     at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.1.7.RELEASE.jar:4.1.7.RELEASE]
18.     at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717) ~[spring-aop-4.1.7.RELEASE.jar:4.1.7.RELEASE]
19.