The specific error you mentioned will be fixed in next release but, we looked at the library and found some problems with it, like the fact that the following equations in SphericalContactSurface:
connect(shape.frame_a, frame_a);
connect(shape.frame_a, contact_a.frame);
and in one of its inherited class PartialContactSurface:
connect(frame_a, fixedFrame.frame_a) ;
connect(fixedFrame.frame_a, body.frame_a);
connect(frame_a, contact_a.frame);
create an over-constrained connection set.
There are dedicated Modelica functions to solve this issue, therefore I suggest you report it to the library developers.