Help Fixing Fan Template

So I have looked through a bunch of posts about the changes for templates but apparently my brain isn’t wired correctly to figure this out. I get the error about default in my logs and here’s my code, can someone share where to add the default info?

fan:
  - platform: template
    fans:
      jrs_bedroom_window_fan:
        friendly_name: "JR's Bedroom Window Fan"
        value_template: "{{ states('light.jr_s_bedroom_window_fan') }}"
        speed_count: 100
        percentage_template: "{{(state_attr('light.jr_s_bedroom_window_fan','brightness') | int / 255*100) | round()}}"
        turn_on:
          service: light.turn_on
          entity_id: light.jr_s_bedroom_window_fan
        turn_off:
          service: light.turn_off
          entity_id: light.jr_s_bedroom_window_fan
        set_percentage:
          service: light.turn_on
          entity_id: light.jr_s_bedroom_window_fan
          data_template:
            brightness_pct: "{{percentage}}"
        set_preset_mode:
          service: light.turn_on
          entity_id: light.jr_s_bedroom_window_fan
          data_template:
            brightness: >
              {% set mapper = {'Off' : 0, 'Low': 100, 'Medium': 170, 'High': 255} %}
              {{ mapper[preset_mode] }}
        preset_modes:
          - "Off"
          - "Low"
          - "Medium"
          - "High"