Dump to json fails if mj model contains no meshes

[Nate711]

I had a case where my mujoco model had only geometry (boxes, spheres, etc) and no meshes. When I tried to use the HTML visualizer with this model (HTML(html.render(brax_sys, rollout))), I got an error in the json dumper because mj_mode.nmeshes returned 0 and this value was not correctly handled.

brax/brax/io/json.py

Line 174 in 3c109cf

vert, face = _get_mesh(sys.mj_model, sys.geom_dataid[id_])

[btaba]

Thanks for the bug report! We'll send out a fix shortly

[btaba]

This should be fixed in 0825bcb , please let us know if that doesn't work! Closing for now