Не могу разобраться с module
<!DOCTYPE html>
<html>
<head>
<title>Parcel Sandbox</title>
<meta charset="UTF-8" />
</head>
<body>
<button id='btn' >Start</button>
<div id="app"></div>
<script src="src/index.js">
</script>
<script type='module'>
import {greet} from './say.js'
const helloW = document.getElementById('btn')
helloW.addEventListener('click', greet);
</script>
</body>
</html>
say.js
export default function greet() { // no function name
alert(`Hello World`);
}