We have a React Native app that uses Redux and we've just converted most of it from Javascript to Typescript. I'm new new to Typescript so bear with me here.
As simply as i can, here's an explanation of the problem. There are two screens: SignIn and Settings (not our real screens but it gets the point across).
In the Redux state, there's an object:
user: { // Whatever user properties we store, id etc}When a user signs in, user is set. Until then, it's null, so user: User | null.
We use createSelector from reselect to fetch the user.The user is fetched on the Settings page and it can technically be null if the user has managed to navigate there without signing in, though this isn't a real use case. To reach the Settings page, you have to sign in. And when you sign in, the user can no longer be null.
In the Settings page, when accessing e.g. user.id, tsc says:
error TS2531: Object is possibly 'null'
How should this be handled? Is there a way to tell Typescript (or tsc, really) that there's no way user can be null on this particular screen? Or should we add a check in each screen making sure user isn't null (even though it shouldn't be possible®)?
I prefer not to suppress the typescript error, if at all possible.
Thank you.