In https://github.com/openjdk/jdk/pull/3583/commits, there is a github check that ended up in conclusion "stale", with completed_at "null". This is causing a NPE to be thrown in the PR bot:

java.lang.NullPointerException: text
at java.base/java.util.Objects.requireNonNull(Objects.java:233)
at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1951)
at java.base/java.time.ZonedDateTime.parse(ZonedDateTime.java:600)
at java.base/java.time.ZonedDateTime.parse(ZonedDateTime.java:585)
at org.openjdk.skara.forge/org.openjdk.skara.forge.github.GitHubPullRequest.lambda$checks$9(GitHubPullRequest.java:410)
at java.base/java.util.stream.Collectors.lambda$toMap$68(Collectors.java:1667)
at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
at org.openjdk.skara.forge/org.openjdk.skara.forge.github.GitHubPullRequest.checks(GitHubPullRequest.java:402)
at org.openjdk.skara.bots.pr/org.openjdk.skara.bots.pr.CheckWorkItem.currentCheckValid(CheckWorkItem.java:109)
at org.openjdk.skara.bots.pr/org.openjdk.skara.bots.pr.CheckWorkItem.run(CheckWorkItem.java:223)
at org.openjdk.skara.bot/org.openjdk.skara.bot.BotRunner$RunnableWorkItem.run(BotRunner.java:90)
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at java.base/java.lang.Thread.run(Thread.java:831)