Removes empty array from script content

Before:

```js
<script id="__LOADABLE_REQUIRED_CHUNKS__" type="application/json">[]</script>
```

After:

```js
<script id="__LOADABLE_REQUIRED_CHUNKS__" type="application/json"></script>
```

Which [loadable/components](https://github.com/smooth-code/loadable-components/) relies on, otherwise it blows up!