Summary:
From exception logging, found crashes due to `Attempt to invoke virtual method 'int android.view.ViewGroup.getChildCount()' on a null object reference`. Tracing through the stack, it appears the constructor for `ViewGroup` conditionally calls `initializeScrollbarsInternal()`, which in turn calls `getChildCount()`. However `ReactModalHostView` overrides `getChildCount()`, so `getChildCount()` is called before `ReactModalHostView` constructor completes, resulting in null reference when accessing `mHostView` from `getChildCount()`.
## Changelog
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[Android] [Fixed] - Fix crash on initialize modal
Pull Request resolved: https://github.com/facebook/react-native/pull/35380
Test Plan: In the rn-tester project, display a modal.
Reviewed By: javache, cipolleschi
Differential Revision: D41392235
Pulled By: ryancat
fbshipit-source-id: ce78e4d458ad41769e78139ea0a8a038384e830d
