403 · Forbidden
type: https://tennisapi.dev/docs/errors/http-403
What it means
The key is valid but the plan does not include this: another sport on a Starter key, data older than the plan's history window, or WebSockets without the add-on.
How to fix it
error.code names the reason (GAME_NOT_INCLUDED, HISTORY_WINDOW_EXCEEDED, WEBSOCKETS_REQUIRED) and the message names the plan that includes it.