2 weird bugs while working with sample project of pencilKit (PencilKitDraw)

I'm trying to customize CanvasView by stacking canvasViews.
If user draw on a canvasView, the stroke will be passed to another canvasView and got delete in original canvasView.

It works quite well but sometimes a stroke just got deleted and not being sent to another canvasView.
It shows those 2 errors, I guess the first error occurs because after user stop using tool, Apple Pencil still send info to canvasView. But I don't know why it happened and why this error deleted a stroke on screen.

The second error says me nothing.

I think i need more context to be able to fix the bugs.

PencilKitDraw[6594:2849236] [Stroke Generator] Missed updates at end of stroke: 2 (total points: 69)

PencilKitDraw[6594:2848789] [] Drawing did change that is not in text.
2 weird bugs while working with sample project of pencilKit (PencilKitDraw)
 
 
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