```ts
export function chunk<T>(items: readonly T[], size: number): T[][] {
  if (!size || size < 1) {
    throw new Error("Size must be a positive integer");
  }

  return items.reduce((acc, item, index, array) => {
    const end = Math.min(index + size, array.length);
    acc.push(array.slice(index, end));
    return acc;
  }, []);
}
```