MutableErrorLiveData.kt

class MutableErrorLiveData<T> : MutableLiveData<Notification<T>>() {
  fun observe(owner: LifecycleOwner, onNext: (T) -> Unit, onError: (Throwable) -> Unit) {
    observe(owner, Observer { notification ->
      notification ?: return@Observer
      if (notification.isOnNext) {
        onNext(notification.value!!)
      } else if (notification.isOnError) {
        onError(notification.error!!)
      }
    })
  }

  fun getNextValue(): T? {
    val notification = value
    if (notification == null) {
      return null
    }
    if (notification.isOnNext) {
      return notification.value!!
    }
    return null
  }

  fun postNextValue(t: T) {
    postValue(Notification.createOnNext(t))
  }

  fun postErrorValue(t: Throwable) {
    postValue(Notification.createOnError(t))
  }
}