```ts
function chunk<T>(items: readonly T[], size: number): T[][] {
  if (!Number.isInteger(size) || size <= 0) throw new Error("Size must be a positive integer");
  if (items.length === 0) return [];

  const result: T[][] = [];
  for (let i = 0, j = items.length; i < j; i += size) {
    result.push(items.slice(i, Math.min(i + size, j)));
  }
  return result;
}
```