Directly after initializing the RevenueCat SDK in my AppDelegate.didFinishLaunchingWithOptions method, I call `Purchases.shared.appUserID`. I briefly looked into the implementation and saw that `IdentityManager.currentAppUserId` (which is used by `Purchases.shared.appUserID` to retrieve the actual id) uses a `fatalError` when no cached app user id is present:
```
var currentAppUserID: String {
guard let appUserID = self.deviceCache.cachedAppUserID else {
fatalError(Strings.identity.null_currentappuserid.description)
}
return appUserID
}
```
My setup:
```
Purchases.configure(
with: Configuration.Builder(withAPIKey: "...")
.build()
)
Purchases.shared.delegate = self
let appUserId = Purchases.shared.appUserID // <- safe?
```
I assume, that the initialization process via `Purchases.configure` is synchronous and that I can safely call `Purchases.shared.appUserID` as shown in the code snippet above. Is this correct or are there any scenarios in which this will crash or yield an invalid id?
