Crash if FixedConstraint is not present

[epernod]

[ERROR] [InterventionalRadiologyController(DeployController)] No fixedConstraint found.

########## SIG 11 - SIGSEGV: segfault ########## sofa::helper::BackTrace::dump sofa::helper::BackTrace::sig seh_filter_exe seh_filter_exe _C_specific_handler _chkstk RtlRaiseException KiUserExceptionDispatcher sofa::component::constraint::projective::ProjectToLineConstraint<sofa::defaulttype::StdVectorTypes<sofa::type::Vec<2,double>,sofa::type::Vec<2,double>,double> >::clearConstraints sofa::component::controller::interventionalradiologycontroller::InterventionalRadiologyController<sofa::defaulttype::StdRigidTypes<3,double> >::fixFirstNodesWithUntil