Fix of "Slicer crashes when slicing for flexible filament" #2988
Fix of "Slicer crashes when slicing for flexible filament" #2988

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