self.iframe is undefined

[darkcavalry]

Hello,

I just created a test file contains

<script src="plugins/jquery/jquery-3.4.1.min.js"></script>
<script src="node_modules/vvvebjs/libs/builder/builder.js"></script>
<script src="node_modules/vvvebjs/libs/builder/undo.js"></script>
<script src="node_modules/vvvebjs/libs/builder/inputs.js"></script>
<script src="node_modules/vvvebjs/libs/builder/components-bootstrap4.js"></script>

<script>
Vvveb.Builder.init("about:blank", function() {
    Vvveb.Builder.setHtml('<p>Hello</p>');
});
</script>

when I run this page, console.log says ;

Uncaught TypeError: self.iframe is undefined
    _loadIframe http://localhost/node_modules/vvvebjs/libs/builder/builder.js:440
    init http://localhost/node_modules/vvvebjs/libs/builder/builder.js:394

Whats wrong on my code?

Thanks.