[Kotlin, rxjava and room] - how to always get a value from Maybe

gistfile1.txt

class Optional<out M>(val data: M?)

@Dao
interface PatientDao {

  @Query("SELECT * FROM $patientTableName LIMIT 1")
  fun getFirst(): Maybe<User>

}

val loggedInUser: Single<Optional<User>>
    get() = userDao.getFirst()
        .toSingle()
        .map { Optional(it) }
        .onErrorResumeNext { Single.just(Optional(null)) }