line 139: test for v_plot

ChangeLog

@@ -1,3 +1,7 @@
+11-01-18 Holger Vogt
+ * plotcurv.c: line 139 test for existance of v_plot before comparing 
+  pl_scale
+  
 11-01-16 Holger Vogt
  * com_cdump.c: remove compiler warnings
  * 1-f-code.c, 1-f-code.h, vsrc.c, vsrcacct.c, vsrcdefs.h,

src/frontend/plotting/plotcurv.c

@@ -136,7 +136,7 @@ ft_graf(struct dvec *v, struct dvec *xs, bool nostart)
             dy = isreal(v) ? v->v_realdata[i] : 
                     realpart(&v->v_compdata[i]);
 	    if ((i == 0 || (dir > 0 ? lx > dx : dir < 0 ? lx < dx : 0))
-		&& xs->v_plot->pl_scale == xs)
+		&& xs->v_plot && xs->v_plot->pl_scale == xs)
 	    {
 		gr_point(v, dx, dy, lx, ly, 0);
 	    } else {