handle empty "points" data properly

pd/src/g_template.c

@@ -3513,9 +3513,9 @@ static void svg_togui(t_svg *x, t_template *template, t_word *data)
         x->x_type == gensym("polygon"))
     {
         int i, n = x->x_nargs;
-        gui_s("points");
         if (x->x_nargs)
         {
+            gui_s("points");
             gui_start_array();
             for (i = 0; i < x->x_nargs; i++)
                 gui_f(fielddesc_getcoord(&x->x_vec[i], template, data, 1));