```ts
/** The text, cut to limit characters with an ellipsis when it is longer; if limit is less than 3, throws an Error. */
export function truncate(text: string, limit: number): string {
  if (!Number.isInteger(limit) || limit < 3) {
    throw new Error("Limit must be an integer of at least 3.");
  }
  return text.length <= limit ? text : `${text.slice(0, limit - 4)}...`;
}
```