## The symptom
Using react-native-purchases in an Expo Go / managed workflow app crashed with:
```
Invariant Violation: new NativeEventEmitter() requires a non-null argument
```
when calling `Purchases.configure` or `Purchases.setup`. The native module was
not linked, so the bridge object was null. The crash happened on both
`Purchases.setup` and `Purchases.configure` calls.
## The fix
1. Upgrade react-native-purchases to 5.0.0. A reporter confirmed the 5.0.0
release works in the managed Expo workflow; that release made the
managed-workflow install path work.
2. In Expo Go specifically, native modules are not available. Use a development
build (EAS) instead, per RevenueCat's Expo docs.
## The rule
`NativeEventEmitter requires a non-null argument` always means the native
module is not linked in your build. In Expo Go that is expected (no custom
native modules); the answer is a dev build, not a config tweak.