TypeError: Cannot read properties of undefined (reading 'id')

[oxSaturn]

Here's a bug from https://onchainkit.xyz/guides/tailwind page:

https://github.com/wevm/vocs/blob/879f297e5cfaceb592044802b85bf4d179842fbd/src/app/components/Outline.tsx#L123

There's no check of accessing an index out of bound, items could be [].