[Schema Inaccuracy] `POST` `/app/installations/{installation_id}/access_tokens` sometimes returns `{}`

[bigfootjon]

Schema Inaccuracy

Calling the above API sometimes returns an empty object, this is not correct according to the schema as this field is not nullable but it could be valid if token and expires_at are marked as nullable.

Reproduction Steps

Requires an app, then call the above API on it.

[nickfloyd]

Thanks for submitting an issue! I've routed this internal to the team that owns the endpoint so it can be addressed.