From 84759f6394feb5c6f64a0b1648e52e7744883692 Mon Sep 17 00:00:00 2001
From: Joseph Bryan <joemfb@gmail.com>
Date: Sat, 31 Mar 2018 12:06:10 -0400
Subject: [PATCH] adds a cell check for the sample of the +roll gate

---
 jets/b/roll.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/jets/b/roll.c b/jets/b/roll.c
index 4700d3c99..1d047df48 100644
--- a/jets/b/roll.c
+++ b/jets/b/roll.c
@@ -18,8 +18,13 @@
     }
     else {
       u3_noun gim = u3k(u3h(a));
-      u3_noun zor = u3k(u3r_at(u3x_sam_3, b));
-      u3_noun daz = u3n_slam_on(u3k(b), u3nc(gim, zor));
+      u3_noun zor = u3r_at(u3x_sam, b);
+
+      if ( c3n == u3du(zor) ) {
+        return u3m_bail(c3__exit);
+      }
+
+      u3_noun daz = u3n_slam_on(u3k(b), u3nc(gim, u3k(u3t(zor))));
       u3_noun vel = u3i_molt(u3k(b), u3x_sam_3, daz, 0);
 
       if ( u3_none == vel ) {