Fix [#31430] part 2: crash in iTaSC when end effector is a fixed bone. This situation was causing access to invalid index in the joint angle array although the end effector doesn't need any joint angle to compute its pause. Fixed this by changing the internal API of joint array: return pointer instead of reference so that NULL pointer can be returned instead of crashing when the index is invalid.

intern/itasc/Distance.cpp

@@ -189,7 +189,7 @@ void Distance::updateKinematics(const Timestamp& timestamp)
 void Distance::updateJacobian()
 {
     for(unsigned int i=0;i<6;i++)
-        m_chiKdl(i)=m_chi(i);
+        m_chiKdl[i]=m_chi[i];
 
     m_fksolver->JntToCart(m_chiKdl,m_internalPose);
     m_jacsolver->JntToJac(m_chiKdl,m_jac);