Handlebars/Mustache plugin problem with script-tags

I have a strange problem with this plugin (sorry, if this question doesn't belong here - couldn't find an appropriate branch).

I have somtething like this in a template:

<div class="wrappert">

    <div id="filter"></div>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script src="/my_api/api.js?v={{jsMtime}}"></script>
    <link rel="stylesheet" href="/my_api/api.css?v={{jsMtime}}" />
    <script>
        initFilter('#filter', {
            type: 'testtype',
            endpoint: '/api/v1/api_endpoint',
            resultView: 'the-grid',
            filter: {},
            disabled: [],
            hidden: [],
        })
    </script>
</div>

Now, when I try to edit the text between the <script>…</script> tags, I can't type. Every character I type is immediately deleted again.

Everything outside the script-tags works perfectly.

Any ideas what this could be?