Fix of SPE-987 (Slicer crash when layers are selected in right panel and settings is added)
Fix of SPE-987 (Slicer crash when layers are selected in right panel and settings is added)

prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r,prusa3d/Slic3r