Template gives errors when starting HA

Hello,

I have the openweathermap integration which I use to create my weather station.

This works fine, but I see some warnings in the log…what is wrong in my template ?

      - name: weather_onecall_hourly_03
        picture: /local/weatherstation/forecast/clean/{{ state_attr('weather.OWM_onecall_hourly', 'forecast')[3].condition }}.png

Logger: homeassistant.helpers.template
Source: helpers/template.py:458
First occurred: 07:07:41 (16 occurrences)
Last logged: 07:07:41

Template variable error: None has no element 3 when rendering '/local/weatherstation/forecast/clean/{{ state_attr('weather.OWM_onecall_hourly', 'forecast')[3].condition }}.png'
Template variable error: None has no element 4 when rendering '/local/weatherstation/forecast/clean/{{ state_attr('weather.OWM_onecall_hourly', 'forecast')[4].condition }}.png'
Template variable error: None has no element 5 when rendering '/local/weatherstation/forecast/clean/{{ state_attr('weather.OWM_onecall_hourly', 'forecast')[5].condition }}.png'
Template variable error: None has no element 6 when rendering '/local/weatherstation/forecast/clean/{{ state_attr('weather.OWM_onecall_hourly', 'forecast')[6].condition }}.png'
Template variable error: None has no element 7 when rendering '/local/weatherstation/forecast/clean/{{ state_attr('weather.OWM_onecall_hourly', 'forecast')[7].condition }}.png'

The strange thing is that I have that template 8 times (from index 0 to 7) and it gives only errors on index 3 till 7 (not on 0 till 2) ?

Any idea ?

Is it really called with capitals?

Dev tools → Templates may not be always 100% trusted: