Steps to reproduce:

If out try to follow tutorial on "https://www.zabbix.com/documentation/current/en/devel/modules/tutorials/widget" or directly use "https://www.zabbix.com/documentation/current/assets/en/devel/modules/examples/lesson_gauge_chart.zip" the widget will not work.

Let me know if you need further details, to reproduce the issue try to import the proposed widget is enough.