Better error message when crashing because of an invalid Remove operation

Summary:
Error messages like P131885276 don't help debugging, even when all mount instructions are logged to logcat. This log would help identify the incorrect mount instruction.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D21735940

fbshipit-source-id: 16ff315c11ccafdd75d0ad9c7c60b7be2cd73202

ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/MountingManager.java

@@ -242,6 +242,17 @@ public class MountingManager {
       throw new IllegalStateException("Unable to find view for tag " + parentTag);
     }
 
+    if (parentView.getChildCount() <= index) {
+      throw new IllegalStateException(
+          "Cannot remove child at index "
+              + index
+              + " from parent ViewGroup ["
+              + parentView.getId()
+              + "], only "
+              + parentView.getChildCount()
+              + " children in parent");
+    }
+
     getViewGroupManager(viewState).removeViewAt(parentView, index);
   }