java.lang.IllegalStateException: Exception thrown on Scheduler.Worker thread. Add onError handling.

[y2k]

java.lang.IllegalStateException: Exception thrown on Scheduler.Worker thread. Add `onError` handling.
    at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:60)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:422)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:152)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:265)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:818)
Caused by: rx.exceptions.OnErrorNotImplementedException
    at rx.Observable$27.onError(Observable.java:7923)
    at rx.observers.SafeSubscriber._onError(SafeSubscriber.java:159)
    at rx.observers.SafeSubscriber.onError(SafeSubscriber.java:120)
    at rx.internal.operators.OperatorMap$1.onError(OperatorMap.java:48)
    at rx.exceptions.Exceptions.throwOrReport(Exceptions.java:187)
    at rx.internal.operators.OperatorMap$1.onNext(OperatorMap.java:56)
    at y2k.joyreactor.common.ObservableExtensionsKt$ioObservable$1$1.call(ObservableExtensions.kt:26)
    at rx.internal.schedulers.ScheduledAction.run(ScheduledAction.java:55)
    ... 7 more
Caused by: kotlin.KotlinNullPointerException
    at y2k.joyreactor.services.TagListService$getTagForFavorite$1.call(TagListService.kt:34)
    at y2k.joyreactor.services.TagListService$getTagForFavorite$1.call(TagListService.kt:14)
    at rx.internal.operators.OperatorMap$1.onNext(OperatorMap.java:54)
    ... 9 more
Caused by: rx.exceptions.OnErrorThrowable$OnNextValue: OnError while emitting onNext value: null
    at rx.exceptions.Exceptions.throwOrReport(Exceptions.java:187)
    at rx.internal.operators.OperatorMap$1.onNext(OperatorMap.java:56)
    ... 9 more

[guijia162]

i‘m the same error,how do you deal it?