NullPointerException error

Plugins Alerting
1

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
OpenSearch - 2.13.0
Alerting plugin - 2.13.0.0
Environment - Docker
Server OS - Ubuntu 20.04.6
Describe the issue:
I added some alert monitors and it initially worked fine then suddenly stopped triggering,when I checked the logs saw the following NullPointerException error.

I tried deleting and adding the monitors again which got the alerts to trigger again but NPE error is still there in the logs.Then tried deleting the alerting plugin altogether,and also .opensearch-alerting-* and .opendistro-alerting* indices which were there, but still see the same error despite removing the plugin.Did i forget to delete any other alerting plugin related stuff ? Would appreciate any help regarding fixing this NPE issue.

**Logs **:

[2024-11-17T05:55:24,491][ERROR][o.o.b.OpenSearchUncaughtExceptionHandler] [opensearch-node1] uncaught exception in thread [DefaultDispatcher-worker-1]
java.lang.NullPointerException: null
	at org.opensearch.alerting.MonitorRunnerService$runJob$2.invokeSuspend(MonitorRunnerService.kt:335) ~[opensearch-alerting-2.13.0.0.jar:2.13.0.0]
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33) [kotlin-stdlib-1.8.21.jar:1.8.21-release-380(1.8.21)]
	at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:233) [kotlinx-coroutines-core-1.1.1.jar:?]
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:594) [kotlinx-coroutines-core-1.1.1.jar:?]
	at kotlinx.coroutines.scheduling.CoroutineScheduler.access$runSafely(CoroutineScheduler.kt:60) [kotlinx-coroutines-core-1.1.1.jar:?]
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:742) [kotlinx-coroutines-core-1.1.1.jar:?]
	at org.opensearch.alerting.MonitorRunnerService$runJob$2.invokeSuspend(MonitorRunnerService.kt:335)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:233)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:594)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.access$runSafely(CoroutineScheduler.kt:60)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:742)
uncaught exception in thread [DefaultDispatcher-worker-1]
java.lang.NullPointerException
	at org.opensearch.alerting.MonitorRunnerService$runJob$2.invokeSuspend(MonitorRunnerService.kt:335)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(Dispatched.kt:233)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:594)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.access$runSafely(CoroutineScheduler.kt:60)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:742)