App launches without crashing on supported OS versions

A crash on launch is the highest-severity rejection — the reviewer cannot evaluate any other part of the app. Apple tests on multiple OS versions and device types; an unhandled exception in root initialization code (unguarded useEffect, top-level JSON.parse, missing optional chaining) will crash on at least one configuration. CWE-390 (detection of error condition without action) and ISO 25010:2011 fault-tolerance both classify this as a fundamental reliability failure. One uncaught rejection in a startup async chain means the entire binary is rejected.

Add a root error boundary in App.tsx and wrap all startup async operations in try/catch.

// App.tsx
import { ErrorBoundary } from 'react-error-boundary';

export default function App() {
  return (
    <ErrorBoundary FallbackComponent={({ error }) => (
      <View><Text>Something went wrong. Please restart the app.</Text></View>
    )}>
      <NavigationContainer>
        <RootNavigator />
      </NavigationContainer>
    </ErrorBoundary>
  );
}

For startup data fetching, always add a catch block: useEffect(() => { fetchConfig().catch(console.error); }, []). Test launch on the minimum supported OS version using Simulator (iOS) or AVD (Android) before every submission.