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