Added another safety check to 'demo_changegeometry'.
Added another safety check to 'demo_changegeometry'.

olitheolix/azrael,daviddeng/azrael,olitheolix/azrael,daviddeng/azrael,olitheolix/azrael,daviddeng/azrael,olitheolix/azrael,daviddeng/azrael,olitheolix/azrael,daviddeng/azrael