IndexArrayOutOfBounds exception in job progress chart generation

Stack trace obtained :

SEVERE: Task threw exception: java.lang.ArrayIndexOutOfBoundsException: 6
java.util.concurrent.ExecutionException: java.lang.ArrayIndexOutOfBoundsException: 6
at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:222)
at java.util.concurrent.FutureTask.get(FutureTask.java:83)
at dk.netarkivet.common.lifecycle.PeriodicTaskExecutor.checkExecution(PeriodicTaskExecutor.java:197)
at dk.netarkivet.common.lifecycle.PeriodicTaskExecutor.access$500(PeriodicTaskExecutor.java:47)
at dk.netarkivet.common.lifecycle.PeriodicTaskExecutor$1.run(PeriodicTaskExecutor.java:176)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 6
at dk.netarkivet.harvester.harvesting.monitor.StartedJobHistoryChartGen$TimeAxisResolution.findTimeUnit(StartedJobHistoryChartGen.java:137)
at dk.netarkivet.harvester.harvesting.monitor.StartedJobHistoryChartGen.generatePngChart(StartedJobHistoryChartGen.java:372)
at dk.netarkivet.harvester.harvesting.monitor.StartedJobHistoryChartGen$ChartGen.run(StartedJobHistoryChartGen.java:197)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:181)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:205)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)