Crash playing around layers

[grofaty]

I have downloaded Pinta 1.8 development for Ubuntu 20.04 from
https://github.com/PintaProject/Pinta/actions/runs/450000006

I was playing around Layers, adding new one, moving them deleting them and then crash appears.
Sorry I don't have exact step-by-steps instructions. Hope crash error can give you some clue.

Pinta: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')
   at Pinta.Gui.Widgets.CanvasRenderer.Render(List`1 layers, ImageSurface dst, Point offset)
   at Pinta.Gui.Widgets.PintaCanvas.OnDrawn(Context context)
   at Gtk.Widget.Drawn_cb(IntPtr inst, IntPtr cr)

[Cameron White (cameronwhite91)]

I haven't been able to reproduce this yet - it's not immediately clear to me how that error would occur in CanvasRenderer.Render()