```ts
/**
 * Splits an array into consecutive groups of at most size elements.
 * @param items - The array to split.
 * @param size - The maximum size of each group.
 * @returns An array of groups.
 */
export function chunk<T>(items: readonly T[], size: number): T[][] {
  if (size <= 0 || !Number.isInteger(size)) {
    throw new Error('Size must be a positive integer');
  }
  return items.length === 0 ? [] : Array.from({ length: Math.ceil(items.length / size) }, (_, i) => items.slice(i * size, i * size + size));
}
```