https://www.zabbix.com/documentation/current/en/devel/modules/tutorials/widget

I've tried to perform the steps with zabbix 6.4.0 (when the how-to doc was written, I guess) and it was almost working.
Still I could not get latest value displayed, just a spinning icon was displayed. 

But when I copied and tried to use the module on 6.4.3 - I get the "Unexpected server error." when trying to add a widget on dashboard.

I reached "Add JavaScript to the widget" step from the doc and did not implement it.

 

I'm attaching the module I made manually by copy-pasting code from the doc, to be 100% identically.
lesson_gauge_chart.zip