You're attempting to render a <Reorder.Group> component without passing a values prop.

<Reorder.Group />

<Reorder.Group> requires a values array.

const [items, setItems] = useState([0, 1, 2])

return (
  <Reorder.Group values={items} onReorder={setItems}>

Each item in the values array must be passed to a Reorder.Item component:

    {items.map((item) => <Reorder.Item key={item} value={item} />)}
  <

This is how Reorder.Group knows which Reorder.Item represents which value.