Android - App crashes with ReactRootView inside viewpager

[tdekoning]

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

Steps to Reproduce

(Write your steps here:)

1. Create a native ViewPager with a ReactRootView as content, preferably with some images inside the ReactRootView
2. Swipe fast
3. See this stack trace

Expected Behavior

I would expect no stack trace or errors to occur.

Actual Behavior

Fatal Exception: java.lang.NullPointerException: Attempt to invoke interface method 'void com.facebook.react.uimanager.ReactShadowNode.addChildAt(com.facebook.react.uimanager.ReactShadowNode, int)' on a null object reference
       at com.facebook.react.uimanager.UIImplementation.setChildren(UIImplementation.java:472)
       at com.facebook.react.uimanager.UIManagerModule.setChildren(UIManagerModule.java:436)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.facebook.react.bridge.JavaMethodWrapper.invoke(JavaMethodWrapper.java:374)
       at com.facebook.react.bridge.JavaModuleWrapper.invoke(JavaModuleWrapper.java:162)
       at com.facebook.react.bridge.queue.NativeRunnable.run(NativeRunnable.java)
       at android.os.Handler.handleCallback(Handler.java:739)
       at android.os.Handler.dispatchMessage(Handler.java:95)
       at com.facebook.react.bridge.queue.MessageQueueThreadHandler.dispatchMessage(MessageQueueThreadHandler.java:31)
       at android.os.Looper.loop(Looper.java:158)
       at com.facebook.react.bridge.queue.MessageQueueThreadImpl$3.run(MessageQueueThreadImpl.java:194)
       at java.lang.Thread.run(Thread.java:818)

This occurs after swiping through the ViewPager quickly.

Reproducible Demo

Proposed fix:
Below this line of code: Add the same fix as this one

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. If you think this issue should definitely remain open, please let us know why. Thank you for your contributions.

[mac-cain13]

Think this issue is still relevant and even a fix is proposed. Is there anyone from the team that can apply this fix or confirm that this fix would be the right thing to do so someone else can create a PR?

[ssuchanowski]

Do you have anywhere demo you used to reproduce this?

I get this exception on prod and the change you are proposing looks reasonable but I cannot reproduce it.

[Frank1234]

Here is a very simple demo project that reproduces this bug: #19233 . Sadly, it reproduces not only this bug, but many other bugs as well, in a random manner.

[SudoPlz]

So what is happening is, react-native is trying to manipulate a view (with setChildren) but that view is not found within the node array.

This is an issue I've been facing for a long time but have NO idea how to resolve.
The proposal does not fix the issue, it just outputs a better error log, but the issue remains..

[Frank1234]

All hail SudoPlz! https://gist.github.com/SudoPlz/23ea2dee9772cb39e1e742034cdf8b98

[patrickkempff]

#20025 should fix this