In every example I've seen of this in use, we get either:

const oauthProvider = new OAuthProvider({
	// @ts-expect-error these types are wrong...
	apiHandler,
	// ...
})

Or as in the official demo:

const oauthProvider = new OAuthProvider({
	apiHandler: apiHandler as any,
	// ...
})

Same with defaultHandler

I'm not certain how to recommend fixing this, but it's unfortunate the types aren't friendly here. Could we get this fixed?