sealed class ResponseResult<out T: Any> {
    class Success<out T : Any>(val value: T) : ResponseResult<T>()
    class Failure(val failureType: FailureType) : ResponseResult<Nothing>()
}

//elsewhere
fun getChangeset(token: String?) : ResponseResult<Any> {
	return try {
		ResponseResult.Success(service.getChangeset(token)) //return type is Changeset<Item>
	} catch (t: Throwable) {
		ResponseResult.Failure(exceptionAsFailureType(t))
	}
}

//elsewhere....
fun updateList(token: String?) {
    scope.launch {
		when (val result = getChangeset(token)) {
			is ResponseResult.Success -> result.value //<- not seeing type is Changeset<Item>
			is ResponseResult.Failure -> when (result.value) {
				FailureType.SERVER_ERROR -> // etc
			}
		}
	}
}