Template error handling

template:
#########
  - sensor:
    - name: "Excess solar" # Not strictly EXCESS - It's a guess, shows what solar is producing when nothing coming from the grid
      unique_id: excess_solar
      unit_of_measurement: "W"
      device_class: energy
      state: > # if solar is > 0 and house = 0 then publish solar else publish 0
        {% if (states('sensor.solarman_output_active_power') != 'unknown')
          and (int(states('sensor.solarman_output_active_power')) > 0)
          and (int(states('sensor.house_power_consumption')) == 0) %}
          {{ states('sensor.solarman_output_active_power') }}
        {% else %}
          0
        {% endif %}
    - name: "Weather factor"
      unique_id: weather_factor # Factor for water time multiplier.
      state: >
        {% set ref_temp = 20 %}
        {% set ref_rain = 10 %}
        {% set temp_factor = 5 * ((((float(states('sensor.marybrook_temp_max_0'))) - ref_temp)) / 100) %}
        {% set target_rain = ref_rain * (1 + temp_factor) %}
        {% set likely_rain = float(states('sensor.marybrook_rain_chance_0'))/100 *
          float(states('sensor.marybrook_rain_amount_min_0')) %}
        {% if likely_rain < float(states('sensor.ibusse56_precipitation_today')) %}
          {% set likely_rain = float(states('sensor.ibusse56_precipitation_today')) %}
        {% endif %}
        {% if likely_rain >= target_rain %}
          {% set weather_factor = 0 %}
        {% else %}
          {% set weather_factor = float((target_rain - likely_rain) / ref_rain) %}
        {% endif %}
        {% if weather_factor == 'unavailable' %}
          {% set weather_factor = 1 %}
        {% endif %}
        {{ weather_factor }}