kotlin bug: Parameter specified as non-null is null

kotlin bug: java.lang.IllegalArgumentException: Parameter specified as non-null is null

错误日志

E/CrashHandler: In thread: Thread[main,5,main]
UncaughtException detected: java.lang.IllegalStateException: Fatal Exception thrown on Scheduler.
at io.reactivex.android.schedulers.HandlerSchedulerMethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:793)
Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter object
at io.reactivex.internal.operators.observable.ObservableObserveOnObserveOnObserver.run(ObservableObserveOn.java:252)
at io.reactivex.android.schedulers.HandlerSchedulerMethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:793)

      代码：
      RetrofitApi.getInstance().saveLocationMsg(regionProvinceId, regionCityId, regionAreaId, purchaseName, purchasePhone, userAddress).
                subscribeOn(Schedulers.io()).
                observeOn(AndroidSchedulers.mainThread()).
                subscribe(object : RxSubcriber() {

            override fun onSuccess(t: Any?) {
                if (isViewAttached) {
                    mMvpView.saveCallBack(t)
                }
            }
    
            override fun onError(e: Throwable?) {
                if (isViewAttached) {
                }
                super.onError(e)
            }
        })
    }

​

解决办法： 回调方法参数后面声明加？ 允许为null