From 24fb7585c733ed49d01b070384943e51abef4ff7 Mon Sep 17 00:00:00 2001
From: Alex Shinn <alexshinn@gmail.com>
Date: Thu, 22 Jul 2021 21:43:50 +0900
Subject: [PATCH] set! should guard against exceptions in the var ref lookup
 (fixes issue #762)

---
 eval.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/eval.c b/eval.c
index d3ca1af0..043adeb6 100644
--- a/eval.c
+++ b/eval.c
@@ -790,7 +790,7 @@ static sexp analyze_set (sexp ctx, sexp x, int depth) {
     res = sexp_compile_error(ctx, "bad set! syntax", x);
   } else {
     ref = analyze_var_ref(ctx, sexp_cadr(x), &varenv);
-    if (sexp_lambdap(sexp_ref_loc(ref)))
+    if (sexp_refp(ref) && sexp_lambdap(sexp_ref_loc(ref)))
       sexp_insert(ctx, sexp_lambda_sv(sexp_ref_loc(ref)), sexp_ref_name(ref));
     value = analyze(ctx, sexp_caddr(x), depth, 0);
     if (sexp_exceptionp(ref)) {