Can someone please explain this error message ```Exception i

Question

Can someone please explain this error message ```Exception in thread UI thread coroutine 1 java lang ClassCastException io reactivex Observer$Subclass1 cannot be cast to com nikolam basketpro ui drills selection DrillsSelectionViewModel$fetchDrillTypes$1$disposable$1 at com nikolam basketpro ui drills selection DrillsSelectionViewModel$fetchDrillTypes$1 invokeSuspend DrillsSelectionViewModel kt 37 at kotlin coroutines jvm internal BaseContinuationImpl resumeWith ContinuationImpl kt 33 at kotlinx coroutines DispatchedTask run DispatchedTask kt 56 at java util concurrent Executors$RunnableAdapter call Executors java 511 at java util concurrent FutureTask run FutureTask java 266 at java util concurrent ScheduledThreadPoolExecutor$ScheduledFutureTask access$201 ScheduledThreadPoolExecutor java 180 at java util concurrent ScheduledThreadPoolExecutor$ScheduledFutureTask run ScheduledThreadPoolExecutor java 293 at java util concurrent ThreadPoolExecutor runWorker ThreadPoolExecutor java 1149 at java util concurrent ThreadPoolExecutor$Worker run ThreadPoolExecutor java 624 at java lang Thread run Thread java 748 ``` I get a passing test with correct data but I also get this error code in thread so I dont spam

Nikola Milovic · Answer

This is the test ``` Test fun `will populate livedata with correct value when repository returns correct data` val expectedDrillTypeOne = DrillsType title1 url1 val expectedDrillTypeTwo = DrillsType title2 url2 every mockDrillRepository loadFullDrillType returns Observable just expectedDrillTypeOne expectedDrillTypeTwo drillsSelectionViewModel fetchDrillTypes val data = drillsSelectionViewModel drillsTypeList getOrAwaitValue assertEquals arrayListOf expectedDrillTypeOne expectedDrillTypeTwo data ``` This is the fun ``` fun fetchDrillTypes val list = ArrayList lt DrillsType gt viewModelScope launch io val disposable = repository loadFullDrillType subscribeWith object DisposableObserver lt DrillsType gt override fun onError e Throwable Log d TAG error + e message override fun onNext data DrillsType Log d TAG data is $data list add data override fun onComplete Log d TAG COMPLETE drillsTypeList postValue list compositeDisposable add disposable ``` The app itself works but the tests pass but error is thrown Idk what is happening I had this problem for somewhile and moving the disposable and everything around fixed it I believe I don t remember what I did exactly I d like to understand what is going on