Add extra logs to diagnose null view state issue

Summary:
We still see crashes for T112157805 and this diff is to add missing information to help diagnose the issue better.

We added a line of log to indicate which `mountItem` triggered the exception.

Changelog: [Internal]

Reviewed By: makovkastar

Differential Revision: D42556576

fbshipit-source-id: 4283c34cb18d601ca7b80d3524c9c65cc4ae3f8a

Author: Xin Chen

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

@@ -276,6 +276,10 @@ private boolean dispatchMountItems() {
           // If there's an exception, we want to log diagnostics in prod and rethrow.
           FLog.e(TAG, "dispatchMountItems: caught exception, displaying mount state", e);
           for (MountItem m : mountItemsToDispatch) {
+            if (m == mountItem) {
+              // We want to mark the mount item that caused exception
+              FLog.e(TAG, "dispatchMountItems: mountItem: next mountItem triggered exception!");
+            }
             printMountItem(m, "dispatchMountItems: mountItem");
           }
           if (mountItem.getSurfaceId() != View.NO_ID) {