Don't die when flipper isn't initialized and a plugin is used

Summary: This diff makes sure that the app doesn't die, or dies in a meaningful way if things are misconfigured.

Reviewed By: passy

Differential Revision: D19468273

fbshipit-source-id: 2471c263391906113446af57d795d1199eb1730e

react-native/react-native-flipper/index.d.ts

@@ -64,6 +64,7 @@ declare module 'Flipper' {
   export function registerPlugin(
     pluginId: string,
     runInBackground: boolean,
+    statusCallback: (status: 'noflipper' | 'ok') => void,
   ): void;
   export function send(pluginId: string, method: string, data: string): void;
   export function reportErrorWithMetadata(