void is not valid as a constituent in a union

[mfulton26]

https://github.com/authts/react-oidc-context/blob/8f5d9b47c12831d257eda29c14cab7f1d0134e31/src/AuthProvider.tsx#L42

see no-invalid-void-type | typescript-eslint

I suggest using user: User | undefined or user?: User instead of user: User | void.