Fix: DOMTokenList error when removing section class

- First add a section styling like `p-2`
- Then remove it with `p-0`
- It works, but you get an error in the console

```
Uncaught DOMException: Failed to execute 'add' on 'DOMTokenList': The token provided must not be empty. at addComponentClass
```

- This is because we pass an empty string in the `<option>`