Fix BadTokenException when displaying warning messages

Reviewed By: achen1

Differential Revision: D6651871

fbshipit-source-id: fc7fc118999f0e752636a3142764bd3496e5dc81

Author: mdvacca

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerImpl.java

@@ -9,6 +9,7 @@
 
 package com.facebook.react.devsupport;
 
+import android.app.Activity;
 import android.app.ActivityManager;
 import android.app.AlertDialog;
 import android.content.BroadcastReceiver;
@@ -371,8 +372,8 @@ private void showNewError(
           @Override
           public void run() {
             if (mRedBoxDialog == null) {
-              Context context = mReactInstanceManagerHelper.getCurrentActivity();
-              if (context == null) {
+              Activity context = mReactInstanceManagerHelper.getCurrentActivity();
+              if (context == null || context.isFinishing()) {
                 FLog.e(ReactConstants.TAG, "Unable to launch redbox because react activity " +
                         "is not available, here is the error that redbox would've displayed: " + message);
                 return;
@@ -518,8 +519,8 @@ public void onOptionSelected() {
 
     final DevOptionHandler[] optionHandlers = options.values().toArray(new DevOptionHandler[0]);
 
-    Context context = mReactInstanceManagerHelper.getCurrentActivity();
-    if (context == null) {
+    Activity context = mReactInstanceManagerHelper.getCurrentActivity();
+    if (context == null || context.isFinishing()) {
       FLog.e(ReactConstants.TAG, "Unable to launch dev options menu because react activity " +
               "isn't available");
       return;