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

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