Invalid config for [automation]: line error missing

in my case the line where the error is is not specified… where is the problem or what should I look for to solve?

Logger: homeassistant.config
Source: config.py:455
First occurred: 8 ottobre 2022 23:59:55 (2 occurrences)
Last logged: 8 ottobre 2022 23:59:55

Invalid config for [automation]: string value is None for dictionary value @ data[‘action’][4][‘parallel’][0][0][‘choose’][0][‘sequence’][2][‘choose’][0][‘sequence’][0][‘service’]. Got None. (See ?, line ?).

It is the 5th action of one of your automations.

This is a choose action.

It is the 3rd action in this choose sequence. Which appears to be another choose action.

The first action of this nested choose sequence has an undefined service.