Segfault on list-ref out-of-bound

```
ypsilon -v
Ypsilon 0.9.6-update3 Copyright (c) 2008 Y.Fujita, LittleWing Company Limited.


(define l (list 1 2 3))
(list-ref l 3)
error in list-ref: index out of bounds, 3 as argument 2
(set-car! l l)
(list-ref l 3)
Segmentation fault


```

Original issue reported on code.google.com by `vladimir...@gmail.com` on 10 Dec 2013 at 9:20
