Intended method of accessing session.grant
Migrating a project from Express + Passport in JS to Fastify + Grant in TS. Have hit a snag with `transport: "session"`

```ts
app
  ...
  .register(grant.fastify({
		  defaults: {
			  origin: config.webServer.url,
			  transport: "session",
			  prefix: "/login",
		  },
		  discord: {
			  client_id: auth.discord.ID,
			  secret: auth.discord.secret,
			  scope: "identify",
			  callback: "/dashboard",
		  },
	}))
	...
```

After having reviewed the `grant-types` repo, I am unable to understand how `req.session.grant` is typed.
In the [grant-types](https://github.com/simov/grant-types)/[examples](https://github.com/simov/grant-types/tree/master/examples)/[transport-session](https://github.com/simov/grant-types/tree/master/examples/transport-session)/[fastify.ts](https://github.com/simov/grant-types/blob/master/examples/transport-session/fastify.ts) file I can see the line `const session: GrantSession = req.session.grant`

When I try to translate that to my project, it doesn't work. Typescript prevents me from attempting to access `.grant` because it's not defined on the session object.
![ts(2339)](https://lunus.xyz/iyj6bO.png)

What is the best way to go about working with this?