Fix a bug in MuJoCo's user_mesh.cc that caused meshdir_ to be overwritten when a model was loaded with a nested model.

PiperOrigin-RevId: 675092713
Change-Id: Iad6336141749510bf5544cab9c06533ee1589c08

src/xml/xml_native_reader.cc

@@ -3645,7 +3645,6 @@ void mjXReader::Body(XMLElement* section, mjsBody* body, mjsFrame* frame,
           throw mjXError(0, "could not find body '%s''%s'", body_name.c_str());
         }
         if (mjs_attachBody(pframe, child, prefix.c_str(), "") != 0) {
-          mj_deleteSpec(asset);
           throw mjXError(elem, mjs_getError(spec));
         }
       } else {