Commit 6fd01c5 for zlib

commit 6fd01c555cb32d5bc70d6afae3abb9bed4474e8e
Author: Zheng Yu <dataisland@outlook.com>
Date:   Tue Nov 3 12:33:48 2026 -0800

    Guard debug character classification for Huffman symbols.

diff --git a/trees.c b/trees.c
index 8e4da01..ae90665 100644
--- a/trees.c
+++ b/trees.c
@@ -227,7 +227,7 @@ local void gen_codes(ct_data *tree, int max_code, ushf *bl_count) {
         tree[n].Code = (ush)bi_reverse(next_code[len]++, len);

         Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x (%x) ",
-            n, (isgraph(n) ? n : ' '), len, tree[n].Code, next_code[len] - 1));
+            n, (isgraph(n & 0xff) ? n : ' '), len, tree[n].Code, next_code[len] - 1));
     }
 }