https://github.com/melisgl/named-readtables/commit/6eea56674442b884a4fee6ede4c8aad63541aa5b

From 6eea56674442b884a4fee6ede4c8aad63541aa5b Mon Sep 17 00:00:00 2001
From: Gabor Melis <mega@retes.hu>
Date: Sun, 9 Nov 2025 18:20:21 +0100
Subject: [PATCH] unbreak after SBCL internals change

--- _build/named-readtables/src/cruft.lisp.orig	2024-10-20 15:57:20 UTC
+++ _build/named-readtables/src/cruft.lisp
@@ -219,7 +219,11 @@
                      (grovel-unicode-chars)
                      (let ((reader-fn (svref char-macro-array char-code))
                            (char (code-char (shiftf char-code (1+ char-code)))))
-                       (if reader-fn
+                       ;; In older SBCL, READER-FN may be NIL. Since
+                       ;; commit 00eabf5 ("Make a few mostly-stylistic
+                       ;; tweaks to macro char reading"), this is 0
+                       ;; instead.
+                       (if (and reader-fn (not (eql reader-fn 0)))
                            (yield char)
                            (grovel-base-chars)))))
                (grovel-unicode-chars ()