```ts

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

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