 ```ts
/**
 * Splits an array into consecutive groups of at most size elements,
 * preserving order; the final group is shorter when the length does not divide evenly.
 *
 * @param items The array to be split.
 * @param size The maximum number of items per group. Must be a positive integer.
 * @throws Error if size is less than 1.
 */
export function chunk<T>(items: readonly T[], size: number): T[][] {
  if (!Number.isInteger(size) || size < 1) {
    throw new Error('size must be a positive integer');
  }

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