"can't convert undefined to object" when calling WidgetBase

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What happened?

I'm trying to create a new widget. Following the latest documentation (generated March 2023 apparently), I can't get the widget to work as the browser javascript console always complains with "can't convert undefined to object". This also happens when I copy paste the example basewidget from the documentation (baselight).

The error appears to come from the code behind WidgetBase.call(self, widget_id, url, skin, parameters, monitored_entities, callbacks). In my simple widget, both monitored_entities and callbacks are empty lists.

Version

4.4.2

Installation type

Home Assistant add-on

Relevant log output

Uncaught TypeError: can't convert undefined to object
    WidgetBase http://homeassistant.home:5050/javascript/dashboard.js:344
    baseday_color http://homeassistant.home:5050/compiled_javascript/application.js:3127
    <anonymous> http://homeassistant.home:5050/compiled_javascript/default/livingroom_init.js:84
    jQuery 13
        j
        k
        setTimeout handler*Deferred/then/g/<
        i
        fireWith
        fire
        i
        fireWith
        ready
        R
        EventListener.handleEvent*
        <anonymous>
        <anonymous>
dashboard.js:344:12
    WidgetBase http://homeassistant.home:5050/javascript/dashboard.js:344
    baseday_color http://homeassistant.home:5050/compiled_javascript/application.js:3127
    <anonymous> http://homeassistant.home:5050/compiled_javascript/default/livingroom_init.js:84
    jQuery 13
        j
        k
        (Async: setTimeout handler)
    g
        i
        fireWith
        fire
        i
        fireWith
        ready
        R
        (Async: EventListener.handleEvent)
    <anonymous>
        <anonymous>
        <anonymous>

Relevant code in the app or config file that caused the issue

function baseday_color(widget_id, url, skin, parameters) {

    self = this
    self.widget_id = widget_id
    self.parameters = parameters

    var monitored_entities = []
    var callbacks = []
    
    WidgetBase.call(self, widget_id, url, skin, parameters, monitored_entities, callbacks)  

    function updateColor() {
        var days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
        var colors = ["violet", "red", "orange", "yellow", "green", "blue", "indigo"];
        var date = new Date();
        var dayName = days[date.getDay()];
        var color = colors[date.getDay()];

        $("#day_color_content").html(dayName);
        $("#day_color_content").css("background-color", color);
    }

    updateColor();
    setInterval(updateColor, 1000 * 60 * 60); // Update every hour
}

Anything else?

No response