NPE during activity transition

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.ViewGroup.transformMatrixToLocal(android.graphics.Matrix)' on a null object reference
        at android.app.ActivityTransitionCoordinator.setSharedElementState(ActivityTransitionCoordinator.java:485)
        at android.app.ActivityTransitionCoordinator.setSharedElementState(ActivityTransitionCoordinator.java:583)
        at android.app.EnterTransitionCoordinator.startSharedElementTransition(EnterTransitionCoordinator.java:405)
        at android.app.EnterTransitionCoordinator.-wrap4(EnterTransitionCoordinator.java)
        at android.app.EnterTransitionCoordinator$5$1$1.run(EnterTransitionCoordinator.java:475)
        at android.app.ActivityTransitionCoordinator.startTransition(ActivityTransitionCoordinator.java:836)
        at android.app.EnterTransitionCoordinator$5$1.onPreDraw(EnterTransitionCoordinator.java:472)
        at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:1013)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2510)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1519)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7113)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:927)
        at android.view.Choreographer.doCallbacks(Choreographer.java:702)
        at android.view.Choreographer.doFrame(Choreographer.java:638)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:913)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6780)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386)
Android version: 7.0
Phone model: SM-T813 (gts210vewifixx)
Briar version: 0.16.2 (63befccd)
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