fixed crash with csd renderer when displaying a slice with no csd glyphs visible
fixed crash with csd renderer when displaying a slice with no csd glyphs visible

TheProjecter/braingl,braingl/braingl,braingl/braingl,mhough/braingl,mhough/braingl,TheProjecter/braingl,braingl/braingl,TheProjecter/braingl,mhough/braingl