[node-02] collector [cluster_stats] failed to collect data

[2019-07-22T21:11:40,787][ERROR][o.e.x.m.c.c.ClusterStatsCollector] [node-02] collector [cluster_stats] failed to collect data
java.lang.NullPointerException: null
at org.elasticsearch.xpack.monitoring.collector.cluster.ClusterStatsCollector.doCollect(ClusterStatsCollector.java:108) ~[x-pack-monitoring-7.2.0.jar:7.2.0]
at org.elasticsearch.xpack.monitoring.collector.Collector.collect(Collector.java:88) [x-pack-monitoring-7.2.0.jar:7.2.0]
at org.elasticsearch.xpack.monitoring.MonitoringService$MonitoringExecution$1.doRun(MonitoringService.java:242) [x-pack-monitoring-7.2.0.jar:7.2.0]
at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:37) [elasticsearch-7.2.0.jar:7.2.0]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515) [?:?]
at java.util.concurrent.FutureTask.run(FutureTask.java:264) [?:?]
at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:688) [elasticsearch-7.2.0.jar:7.2.0]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
at java.lang.Thread.run(Thread.java:835) [?:?]


es日志中不断的滚动出现这个错误，如何理解报错的含义？