```ts
function chunk<T>(items: readonly T[], size: number): T[][] {
    if (size <= 0) {
        throw new Error("size must be a positive integer");
    }

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