From f04a729dc93f6f34bc6aec019bdfd820ff32f1a9 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Sun, 4 Feb 2024 17:06:05 +0900
Subject: [PATCH] gc.c (obj_free): check if irep is NULL before
 mrb_irep_decref(); #6161

---
 src/gc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/gc.c b/src/gc.c
index 63d3f1678..a39d4e47f 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -827,7 +827,9 @@ obj_free(mrb_state *mrb, struct RBasic *obj, int end)
     {
       struct RBacktrace *bt = (struct RBacktrace*)obj;
       for (size_t i = 0; i < bt->len; i++) {
-        mrb_irep_decref(mrb, (mrb_irep*)bt->locations[i].irep);
+        const mrb_irep *irep = bt->locations[i].irep;
+        if (irep == NULL) continue;
+        mrb_irep_decref(mrb, (mrb_irep*)irep);
       }
       mrb_free(mrb, bt->locations);
     }