From 702604b18cdbcccc959719116d3983ffc8581222 Mon Sep 17 00:00:00 2001
From: Boris Smilga <boris.smilga@gmail.com>
Date: Mon, 3 May 2021 14:40:52 +0300
Subject: [PATCH] Fixed error occuring in SEQ-TYPE when applied to empty
 strings and vectors. (Was causing failure in test APPLY-PATCH after fixes to
 GitHub issue #5.)

---
 lib.lisp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib.lisp b/lib.lisp
index 2f13e4a..aaeecb4 100644
--- a/lib.lisp
+++ b/lib.lisp
@@ -47,7 +47,7 @@
                 ((stringp x) 'string)
                 ((vectorp x) 'vector)
                 (t (error "Not a sequence")))
-          (if (not (null x))
+          (if (if (listp x) (not (null x)) (plusp (length x)))
               (let ((x0 (elt x 0)))
                 (if (typep x0 'sequence)
                     (seq-type x0)