operator[] doesn't check if the option exists in the values_ map, so it can return a pointer to location outside the map. Fix by returning an empty OptionValue if the option is not found. Signed-off-by: Tomi Valkeinen <tomi.valkeinen@iki.fi> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com> [Kieran: Adjust s_empty naming to 'empty'] Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>