fix(android): crash on resetting borderStyle with props 2.0

[hannojg]

Summary:

The problem

When enabling props 2.0 with the feature flags:

  override fun enableAccumulatedUpdatesInRawPropsAndroid(): Boolean = true
  override fun enableExclusivePropsUpdateAndroid(): Boolean = true
  override fun enablePropsUpdateReconciliationAndroid(): Boolean = true

setting the style for borderStyle to undefined causes a crash:

Screen_recording_20260326_092132.mp4

Expand for crash stack

Error while updating prop borderStyle
java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.String
	at com.facebook.react.uimanager.ViewManagersPropertyCache$StringPropSetter.getValueOrDefault(ViewManagersPropertyCache.java:291)
	at com.facebook.react.uimanager.ViewManagersPropertyCache$PropSetter.updateViewProp(ViewManagersPropertyCache.java:86)
	at com.facebook.react.uimanager.ViewManagerPropertyUpdater$FallbackViewManagerSetter.setProperty(ViewManagerPropertyUpdater.kt:155)
	at com.facebook.react.uimanager.ViewManagerPropertyUpdater$GenericViewManagerDelegate.setProperty(ViewManagerPropertyUpdater.kt:188)
	at com.facebook.react.uimanager.ViewManager.updateProperties(ViewManager.java:102)
	at com.facebook.react.fabric.mounting.SurfaceMountingManager.updateProps(SurfaceMountingManager.kt:635)
	at com.facebook.react.fabric.mounting.SurfaceMountingManager.updateProps(SurfaceMountingManager.kt:598)
	at com.facebook.react.fabric.mounting.mountitems.IntBufferBatchMountItem.execute(IntBufferBatchMountItem.kt:127)
	at com.facebook.react.fabric.mounting.MountItemDispatcher.executeOrEnqueue(MountItemDispatcher.kt:379)
	at com.facebook.react.fabric.mounting.MountItemDispatcher.dispatchMountItems$lambda$7$lambda$6(MountItemDispatcher.kt:269)
	at com.facebook.react.fabric.mounting.MountItemDispatcher.$r8$lambda$4xp_oXLXKRRjXh_WfqmwhGWbzaM(Unknown Source:0)
	at com.facebook.react.fabric.mounting.MountItemDispatcher$$ExternalSyntheticLambda4.invoke(D8$$SyntheticClass:0)
	at com.facebook.react.internal.tracing.PerformanceTracer.trace(PerformanceTracer.kt:46)
	at com.facebook.react.internal.tracing.PerformanceTracer.trace(PerformanceTracer.kt:35)
	at com.facebook.react.fabric.mounting.MountItemDispatcher.dispatchMountItems(MountItemDispatcher.kt:250)
	at com.facebook.react.fabric.mounting.MountItemDispatcher.tryDispatchMountItems(MountItemDispatcher.kt:94)
	at com.facebook.react.fabric.FabricUIManager$DispatchUIFrameCallback.doFrameGuarded(FabricUIManager.java:1581)
	at com.facebook.react.uimanager.GuardedFrameCallback.doFrame(GuardedFrameCallback.kt:42)
	at com.facebook.react.modules.core.ReactChoreographer.frameCallback$lambda$1(ReactChoreographer.kt:58)
	at com.facebook.react.modules.core.ReactChoreographer.$r8$lambda$nSkFhrr5T7rop_XKwzlLov4NLLw(Unknown Source:0)
	at com.facebook.react.modules.core.ReactChoreographer$$ExternalSyntheticLambda0.doFrame(D8$$SyntheticClass:0)
	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1628)
	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1639)
	at android.view.Choreographer.doCallbacks(Choreographer.java:1235)
	at android.view.Choreographer.doFrame(Choreographer.java:1160)
	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1613)
	at android.os.Handler.handleCallback(Handler.java:1070)
	at android.os.Handler.dispatchMessage(Handler.java:125)
	at android.os.Looper.dispatchMessage(Looper.java:333)
	at android.os.Looper.loopOnce(Looper.java:263)
	at android.os.Looper.loop(Looper.java:367)
	at android.app.ActivityThread.main(ActivityThread.java:9287)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:566)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:929)

The bug & its fix

The problem is that we clear the value of borderStyle using NULL:

https://github.com/facebook/react-native/blob/4f908f433044279b7340c1933792b15aa5796a32/packages/react-native/ReactCommon/react/renderer/components/view/platform/android/react/renderer/components/view/HostPlatformViewProps.cpp#L382

where NULL seems to be defined as 0:

so, folly treats this as a 0.0 and we get a double for a value meant to be null / optional.

The fix is to change this to a proper folly nullish-value, as this PR does. This fixes the crash:

Screen_recording_20260326_091533.mp4

(I think there are other places where this is being misused, but i will make individual PRs for those cases!)

Changelog:

[ANDROID] [FIXED] - Fixed crash when enabling props 2.0 and setting borderStyle to undefined

Test Plan:

You can test the crash before with the following code in the playground app:

https://github.com/facebook/react-native/compare/main...hannojg:react-native:hannojg/reproduction-borderstyle-issue?expand=1

You can then test and see how this fix resolves the crash.

[meta-codesync]

@zeyap has imported this pull request. If you are a Meta employee, you can view this in D98322741.

[react-native-bot]

This pull request was successfully merged by @hannojg in 9e058db

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