Remove/hide NaN for sensor with no data

Hi all

I have a template sensor that displays my google home mini’s volume and buttons to set 10%, 20% etc…

The problem is when the googles arent playing this state attribute is hidden and in floorplan that shows as “NaN” on my SVG.

is it possible to somehow hide when unknown or display something else ?

Here is my template

  - platform: template
        value_template: '{{ states.media_player.bathroom_speaker.attributes.volume_level | multiply(100) | round(0)  }}'
        friendly_name: 'Bathroom Volume'
        unit_of_measurement: "%"

And my floorplan

  - name: volume_level
      - sensor.bathroom_mini_volume
      - sensor.bedroom_mini_volume
      - sensor.audio_cast_volume
      - sensor.kitchen_mini_volume
      - sensor.tv_mini_volume
      - sensor.spare_mini_volume
    text_template: '${entity.state ? Math.ceil(entity.state) + "%": "undefined"}'
    class_template: 'return "volume_level";'