From 37e9a5d1f8ec90c2fe1cddd0546655ad2afc1dac Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Mon, 29 Apr 2019 06:07:56 -0700
Subject: backtrace: check next frame for nil.

* share/txr/stdlib/debug.tl (fcall-frame print-trace): Don't
invoke .(loc) method on nx-fr, if it is nil.
---
 share/txr/stdlib/debugger.tl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/share/txr/stdlib/debugger.tl b/share/txr/stdlib/debugger.tl
index 9cd52b61..8eeb9ce2 100644
--- a/share/txr/stdlib/debugger.tl
+++ b/share/txr/stdlib/debugger.tl
@@ -51,7 +51,7 @@
          (args fr.args)
          (name (if (functionp fun)
                  (func-get-name fun)))
-         (loc nx-fr.(loc))
+         (loc (if nx-fr nx-fr.(loc)))
          (kind
            (cond
              ((interp-fun-p fun) "I")
-- 
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