title: One Signal SDK Error with Expo+ReactNative
body: <p>I'm trying to add the OneSignal SDK to my ReactNative project managed by Expo SDK, by following the guide here:</p>
  <p><a href="https://github.com/OneSignal/onesignal-expo-plugin" rel="nofollow noreferrer">Expo One Signal</a></p>
  <p>here is my plugin setup in App.js</p>
  <pre><code>    export default function App() {
    useEffect(() =&gt; {
     ///Other things
      OneSignal.setAppId(Constants.manifest.extra.oneSignalAppId);
    }, []);
  </code></pre>
  <p>unfortunately it doesn't work, first I was getting:</p>
  <pre><code>Invariant Violation: Native module cannot be null.
  at node_modules/react-native/Libraries/Core/ExceptionsManager.js:104:6 in reportException
  at node_modules/react-native/Libraries/Core/ExceptionsManager.js:172:19 in handleException
  at node_modules/react-native/Libraries/Core/setUpErrorHandling.js:24:6 in handleError
  at node_modules/@react-native/polyfills/error-guard.js:49:36 in ErrorUtils.reportFatalError
  at node_modules/metro-runtime/src/polyfills/require.js:204:6 in guardedLoadModule
  at http://127.0.0.1:19000/node_modules/expo/AppEntry.bundle?platform=ios&amp;dev=true&amp;hot=false&amp;minify=false:263808:3 in global code
  
  Invariant Violation: &quot;main&quot; has not been registered. This can happen if:
  * Metro (the local dev server) is run from the wrong folder. Check if Metro is running, stop it and restart it in the current project.
  * A module failed to load due to an error and `AppRegistry.registerComponent` wasn't called.
  at node_modules/react-native/Libraries/Core/ExceptionsManager.js:104:6 in reportException
  at node_modules/react-native/Libraries/Core/ExceptionsManager.js:172:19 in handleException
  at node_modules/react-native/Libraries/Core/setUpErrorHandling.js:24:6 in handleError
  at node_modules/@react-native/polyfills/error-guard.js:49:36 in ErrorUtils.reportFatalError
  </code></pre>
  <p>Then, after opening an issue in GitHub the author suggested my to install:</p>
  <pre><code>yarn add react-native-onesignal
  </code></pre>
  <p>Here is the <a href="https://github.com/OneSignal/onesignal-expo-plugin/issues/55" rel="nofollow noreferrer">Issue</a> on Github.Then I started getting:</p>
  <pre><code>iOS Bundling failed 3417ms
  Unable to resolve module fs from /Users/giulioserra/Documents/App/CTS/node_modules/onesignal-expo-plugin/build/onesignal/withOneSignalIos.js: fs could not be found within the project or in these directories:
    node_modules
  
  If you are sure the module exists, try these steps:
   1. Clear watchman watches: watchman watch-del-all
   2. Delete node_modules and run yarn install
   3. Reset Metro's cache: yarn start --reset-cache
   4. Remove the cache: rm -rf /tmp/metro-*
    29 | exports.xcodeProjectAddNse = exports.withOneSignalIos = void 0;
    30 | const config_plugins_1 = require(&quot;@expo/config-plugins&quot;);
  &gt; 31 | const fs = __importStar(require(&quot;fs&quot;));
  </code></pre>
  <p>I cleared the cache but nothing, It seems so strange since fs package should be included in every node release as far as I know, and suggestions?</p>