title: AssertionError: This root view has already been attached to a catalyst instance manager
body: <p>I have a native Android app that has some fragments inflated with React Native views. </p>
  
  <p>When one of the React Native fragments are added to the backstack and then the backstack gets popped back to the React Native fragment, I get the following error: </p>
  
  <pre><code>E/AndroidRuntime: FATAL EXCEPTION: main
  java.lang.AssertionError: This root view has already been attached to a catalyst instance manager
      at com.facebook.infer.annotation.Assertions.assertCondition(Assertions.java:65)
      at com.facebook.react.ReactRootView.startReactApplication(ReactRootView.java:207)
      at com.vb.easternunion.fragments.ReactFragment.onActivityCreated(ReactFragment.java:52)
      at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:2096)
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1295)
      at android.support.v4.app.BackStackRecord.popFromBackStack(BackStackRecord.java:1038)
      at android.support.v4.app.FragmentManagerImpl.popBackStackState(FragmentManager.java:1742)
      at android.support.v4.app.FragmentManagerImpl$2.run(FragmentManager.java:601)
      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1682)
      at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:541)
      at android.os.Handler.handleCallback(Handler.java:739)
      at android.os.Handler.dispatchMessage(Handler.java:95)
      at android.os.Looper.loop(Looper.java:148)
      at android.app.ActivityThread.main(ActivityThread.java:5417)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
  </code></pre>
  
  <p>Anyone know why I'm getting this error of root view already being attached or how I can reuse the same root view?</p>
  
  <p>My React Fragment looks like this: </p>
  
  <pre><code>public class ReactFragment extends Fragment {
      private ReactRootView mReactRootView;
      private ReactInstanceManager mReactInstanceManager;
      private MainActivity main;
  
      @Override
      public void onAttach(Context context) {
          super.onAttach(context);
  
          main = (MainActivity) getActivity();
  
          mReactRootView = new ReactRootView(context);
          mReactInstanceManager =
                  ((AppManager) getActivity().getApplication())
                          .getReactNativeHost()
                          .getReactInstanceManager();
  
      }
  
      @Override
      public ReactRootView onCreateView(LayoutInflater inflater, ViewGroup group, Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          return mReactRootView;
      }
  
  
      @Override
      public void onActivityCreated(Bundle savedInstanceState) {
          super.onActivityCreated(savedInstanceState);
  
          mReactRootView.startReactApplication(
                  mReactInstanceManager,
                  "AndroidApp",
                  getLaunchOptions()
          );
  
      }
  
      protected
      @Nullable
      Bundle getLaunchOptions() {
          return AppManager.getReactBundle();
      }
  
  
  
      @Override
      public void onDestroyView() {
          super.onDestroyView();
          mReactRootView.unmountReactApplication();
      }
  
  }
  </code></pre>