Steps to reproduce:

1. I followed procedure in https://www.zabbix.com/documentation/current/en/devel/modules/tutorials/widget to create custom widget.
2. Modifying modules/lesson_gauge_chart/views/widget.view.php as follows.
3. <?php
          
          /**
           * Gauge chart widget view.
           *
           * @var CView $this
           * @var array $data
           */
          
           //error(_s('%s', $data['item']));
           $datakeys = array_keys($data);
           error(_s('key of data variable'));
           foreach ($datakeys as $datakey) {            error(_s('%s', $datakey));         }

           
         
          
          (new CWidgetView($data))
              ->addItem([
                  new CTag('h1', true, $data['description']),
                  new CDiv($data['value'] !== null ? $data['value']['value'] : _('No data'))
              ])
              ->show();

Result:

No item related key in $data variable
Please see screenshot.

Expected:
$data variable contains item related key.