WipeTower - fixed a crash in extrude_explicit when called from finish_layer before the first toolchange
WipeTower - fixed a crash in extrude_explicit when called from finish_layer before the first toolchange

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