Cannot set "None" string as light effect - is it a bug?

Hi

This script fails if I set the value of “None” for the “effect” (this is the string Hue uses)

variables:
  effect: "None"
sequence:
  - service: light.turn_on
    target:
      entity_id: light.lounge_left
    data:
      effect: "{{ effect }}"

The error is

“Failed to call service script/test_pendant_effects. string value is None for dictionary value @ data[‘effect’]”

It works if I use a different effect string, say effect: “prism”

I can workaround like this

      - if:
          - condition: template
            value_template: "{{ effect == 'None' }}"
        then:
          - service: light.turn_on
            target:
              entity_id: light.pendant_dining_room
            data:
              effect: None
        else:
          - service: light.turn_on
            target:
              entity_id: light.pendant_dining_room
            data:
              effect: "{{ effect }}"

but is this a bug?
Is there a way I can pass “None” as a string that won’t trigger this error?