From 4f4a775d9e44ae6caac8bdcad573d122aca00c7d Mon Sep 17 00:00:00 2001
From: Richard Hansen <rhansen@rhansen.org>
Date: Mon, 25 Oct 2021 05:19:35 -0400
Subject: [PATCH] Changeset: Improve handling of missing attribute in old pool

---
 src/static/js/Changeset.js | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/src/static/js/Changeset.js b/src/static/js/Changeset.js
index 2df33ec46..d261db748 100644
--- a/src/static/js/Changeset.js
+++ b/src/static/js/Changeset.js
@@ -1563,18 +1563,10 @@ exports.moveOpsToNewPool = (cs, oldPool, newPool) => {
   // order of attribs stays the same
   return upToDollar.replace(/\*([0-9a-z]+)/g, (_, a) => {
     const oldNum = exports.parseNum(a);
-    let pair = oldPool.getAttrib(oldNum);
-
-    /*
-     * Setting an empty pair. Required for when delete pad contents / attributes
-     * while another user has the timeslider open.
-     *
-     * Fixes https://github.com/ether/etherpad-lite/issues/3932
-     */
-    if (!pair) {
-      pair = [];
-    }
-
+    const pair = oldPool.getAttrib(oldNum);
+    // The attribute might not be in the old pool if the user is viewing the current revision in the
+    // timeslider and text is deleted. See: https://github.com/ether/etherpad-lite/issues/3932
+    if (!pair) return '';
     const newNum = newPool.putAttrib(pair);
     return `*${exports.numToString(newNum)}`;
   }) + fromDollar;