Uncaught ReferenceError: h is not defined

[SeregPie]

If I split a .vue file into this

<template src="./template.html"></template>
<script src="./script.js"></script>

I get the following error in the browser console.
Uncaught ReferenceError: h is not defined

For example. You have a HelloWorld.vue file and you create HelloWorld/script.js, HelloWorld/template.html and HelloWorld/index.vue with the content above.