In odoo 16, I have created a custom widget. I am getting error.

var CustomWidgetName = AbstractField.extend({
    FieldRegistry.add('CustomWidgetName', CustomWidgetName);
    return { 
      CustomWidgetName: CustomWidgetName, 
  }; 
});

In browser, I can see only the value of json field. But I need graph which I wrote in json file. And I am getting this message (Missing widget error) in browser console.

Missing widget: CustomWidgetName for field of type text

I used the created widget inside the kanban-box view.

/*?xml version="1.0" encoding="utf-8"?*/

/*odoo*/

/*record id="new_id" model="ir.ui.view"*/

/*field name="name"*/Dashboard/*field*/

/*field name="model"*/new.model.name/*field*/

/*field name="type"*/kanban/*field*/

/*field name="arch" type="xml"*/

/*kanban create="false"*/

/*templates*/

/*t t-name="kanban-box"*/

/*div class="card-body o_dashboard_graph" style="margin:auto;"*/

/*field name="json_value_field" ylabel="y" xlabel="x" graph_type="line" widget="CustomWidgetName"*/

/*/div*/

/*/t*/

/*/templates*/

/*/kanban*/

/*/field*/

/*/record*/

/*/odoo*/