fixed a problem when deleting a part.
fixed a problem when deleting a part.

NeuroRoboticTech/AnimatLabPublicSource,NeuroRoboticTech/AnimatLabPublicSource,NeuroRoboticTech/AnimatLabPublicSource,NeuroRoboticTech/AnimatLabPublicSource,NeuroRoboticTech/AnimatLabPublicSource