Problem playing spotify with a script: KeyError

I’m new to homeassistant and having trouble getting a script to work.

I would like to play a spotify playlist on a google cast group.

For now, I’m just trying to get it to work on a single Google Home Mini called “Kitchen.”

It doesn’t work, and in home-assistant.log I see:

KeyError: ‘Kitchen’

I’m running this on a Mac. Here’s the script:

# Play random playlist and switch to Chromecast
    alias: 'Spotify on Chromecast'
      - service: media_player.select_source
          entity_id: media_player.spotify
          source: Kitchen
      - service: media_player.play_media
          entity_id: media_player.spotify
          media_content_type: playlist
          media_content_id: >
            {%- set plists = ["spotify:user:spotify:playlist:1aoIH3IB2MRfYhD1Z2Y5aK",
               ] -%}
              {% set pindex =  (range(0, (plists | length - 1 ) )|random) -%}
              {{ plists[pindex] }}

Any ideas what I’m doing wrong?