Starting from the code from FreeMotion [example](https://github.com/JuliaComputing/Multibody.jl/blob/8e3f8c1eb3e37a48a37247ba187a402db42dfee5/docs/src/examples/free_motion.md?plain=1#L2) If I want to render `Multibody.render(model, prob)` I have the following error: ``` 'ERROR: Invalid symbol (freeMotion₊Rrel_f₊r_0(t))[1] for `getsym` ```
