[AppRegistry] Avoid using invariant in runApplication to preserve red screen and provide more useful warning

Author: brentvatne

Libraries/ReactNative/AppRegistry.js

@@ -190,13 +190,24 @@ const AppRegistry = {
         () => msg,
       );
     }
-    invariant(
-      runnables[appKey] && runnables[appKey].run,
-      `"${appKey}" has not been registered. This can happen if:\n` +
-        '* Metro (the local dev server) is run from the wrong folder. ' +
-        'Check if Metro is running, stop it and restart it in the current project.\n' +
-        "* A module failed to load due to an error and `AppRegistry.registerComponent` wasn't called.",
-    );
+
+    // NOTE(brentvatne): the original error message here, commented out below,
+    // is not useful to developers in the Expo managed workflow. It also will
+    // prevent any red box error that has occurred while loading the bundle from
+    // being visible to the user. So, we instead warn and give a more tailored
+    // message to help users with debugging the issue.
+    if (!runnables[appKey] || !runnables[appKey].run) {
+      console.warn(`Unable to start your application. Please refer to https://expo.fyi/no-registered-application for more information.`);
+      return;
+    }
+
+    // invariant(
+    //   runnables[appKey] && runnables[appKey].run,
+    //   `"${appKey}" has not been registered. This can happen if:\n` +
+    //     '* 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.\n' +
+    //     "* A module failed to load due to an error and `AppRegistry.registerComponent` wasn't called.",
+    // );
 
     SceneTracker.setActiveScene({name: appKey});
     runnables[appKey].run(appParameters);