NPE in SiteStats compareTo

17-Jun-2020 11:00:36.302 ERROR [QuartzScheduler_Worker-4] org.sakaiproject.sitestats.impl.StatsAggregateJobImpl.startJob Unable to retrieve events due to an unknown cause
java.lang.NullPointerException
        at org.sakaiproject.sitestats.impl.SitePresenceImpl.compareTo(SitePresenceImpl.java:45)
        at org.sakaiproject.sitestats.impl.SitePresenceImpl.compareTo(SitePresenceImpl.java:26)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl$SitePresenceConsolidation.compareTo(StatsUpdateManagerImpl.java:1767)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl$SitePresenceConsolidation.compareTo(StatsUpdateManagerImpl.java:1740)
        at java.util.Arrays.mergeSort(Arrays.java:1372)
        at java.util.Arrays.mergeSort(Arrays.java:1360)
        at java.util.Arrays.legacyMergeSort(Arrays.java:1319)
        at java.util.Arrays.sort(Arrays.java:1310)
        at java.util.Arrays.sort(Arrays.java:1506)
        at java.util.ArrayList.sort(ArrayList.java:1462)
        at java.util.Collections.sort(Collections.java:143)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl.doUpdateSitePresencesObjects(StatsUpdateManagerImpl.java:1408)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl.lambda$doUpdateConsolidatedEvents$4(StatsUpdateManagerImpl.java:998)
        at org.springframework.orm.hibernate4.HibernateTemplate.doExecute(HibernateTemplate.java:341)
        at org.springframework.orm.hibernate4.HibernateTemplate.execute(HibernateTemplate.java:296)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl.doUpdateConsolidatedEvents(StatsUpdateManagerImpl.java:929)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl.collectEvents(StatsUpdateManagerImpl.java:295)
        at org.sakaiproject.sitestats.impl.StatsUpdateManagerImpl.collectEvents(StatsUpdateManagerImpl.java:273)
        at sun.reflect.GeneratedMethodAccessor4665.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
        at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
        at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
        at com.sun.proxy.$Proxy216.collectEvents(Unknown Source)
        at org.sakaiproject.sitestats.impl.StatsAggregateJobImpl.startJob(StatsAggregateJobImpl.java:328)
        at org.sakaiproject.sitestats.impl.StatsAggregateJobImpl.execute(StatsAggregateJobImpl.java:189)
        at org.sakaiproject.component.app.scheduler.jobs.SpringJobBeanWrapper.execute(SpringJobBeanWrapper.java:57)
        at org.quartz.core.JobRunShell.run(JobRunShell.java:202)
        at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:573)
17-Jun-2020 11:00:36.303 INFO [QuartzScheduler_Worker-4] org.sakaiproject.sitestats.impl.StatsAggregateJobImpl.execute Summary: Unable to retrieve events due to: null
17-Jun-2020 11:00:36.304 INFO [QuartzScheduler_Worker-4] org.sakaiproject.sitestats.impl.StatsAggregateJobImpl.execute Finishing job: SiteStats