Widening Error Types in Stream Processing

const preferredProfileStream = (activityId: BSON.ObjectId) => pipe(
    entityStream.userActivity(activityId),
    Stream.map(act => act.preferredProfile),
    Stream.changes,
    Stream.flatMap(profileId => 
      Stream.suspend((): Stream.Stream<
          RuntimeR, 
          RealmDbWrapperError | RealmDbError | ObjectNotFoundError | EntityDoesNotExistError, ActivityProfileData
        > => 
        profileId
          ? entityStream.activityProfile(activityId)
          : Stream.fail(new EntityDoesNotExistError({
            message: `No preferredProfile for UserActivity ${activityId.toHexString()}`
          }))
      ))
  )

export type extractStreamError<S> = S extends Stream.Stream<unknown, infer X, unknown> ? X : never