From 30d68df3966c544ba23f4edb63785d17252968cf Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Sun, 12 Dec 2021 23:50:48 -0500
Subject: [PATCH] Changeset: Add range checks to `makeSplice`

---
 src/static/js/Changeset.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index f753c791..81032b58 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -1491,6 +1491,8 @@ exports.identity = (N) => exports.pack(N, N, '', '');
  * @returns {string}
  */
 exports.makeSplice = (orig, start, ndel, ins, attribs, pool) => {
+  if (start < 0) throw new RangeError(`start index must be non-negative (is ${start})`);
+  if (ndel < 0) throw new RangeError(`characters to delete must be non-negative (is ${ndel})`);
   if (start >= orig.length) start = orig.length - 1;
   if (ndel > orig.length - start) ndel = orig.length - start;
   const deleted = orig.substring(start, start + ndel);