Cannot read property 'indexOf' of undefined

Hello,

I am spinning up a new instance of grapeJS, and immediately everything breaks and I get the following error:

Cannot read property 'indexOf' of undefined at grapes.js:6477

My code looks like the following:

<link href="//unpkg.com/grapesjs/dist/css/grapes.min.css" />
    <script src="//unpkg.com/grapesjs"></script>

    <div id="gjs">
        <h1>Hello World Component!</h1>
    </div>
    <div id="blocks"></div>

    <script>
        $(document).ready(function () {
            grapesjs.init({
                // Indicate where to init the editor. You can also pass an HTMLElement
                container: '#gjs',
                // Get the content for the canvas directly from the element
                // As an alternative we could use: `components: '<h1>Hello World Component!</h1>'`,
                components: '<h1>Hello World component!</h1>'
            });
        });
    </script>

It looks like it is trying to return indexOf on self, but self isn't defined. Can you quickly help me resolve this?

return self.indexOf(item) === index;