```ts
export function chunk<T>(items: readonly T[], size: number): T[][] {
  if (!Number.isInteger(size) || size <= 0) {
    throw new Error('size must be a positive integer');
  }

  const result: T[][] = [];
  let startIndex = 0;

  while (startIndex < items.length) {
    const endIndex = Math.min(startIndex + size, items.length);
    result.push(items.slice(startIndex, endIndex));
    startIndex = endIndex;
  }

  return result;
}
```