```typescript
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.');
  }

  if (items.length === 0) return [];

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