 
     persona_candidates =
       from(e in Persona,
-        where: is_nil(e.thumbnailed) and not is_nil(e.image_url),
+        where: not e.thumbnailed and not is_nil(e.image_url),
         limit: 1_000,
         select: e.id
       )

  def catch_up_thumbnailed(conn, _paar) do
    podcast_candidates =
      from(e in Podcast,
        where: is_nil(e.thumbnailed) and not is_nil(e.image_url),
        limit: 1_000,
        select: e.id
      )

    for _i <- 1..10 do
      episode_candidates =
        from(e in Episode,
          where: not e.thumbnailed and not is_nil(e.image_url),
          limit: 1_000,
          select: e.id
        )
