From 81a721f88025450cf5b6cd81fc3ac787a8e0c9d1 Mon Sep 17 00:00:00 2001
From: Bruno Windels <bruno@windels.cloud>
Date: Fri, 11 Jun 2021 11:04:48 +0200
Subject: [PATCH] make equality stable in comparator for reaction

---
 src/domain/session/room/timeline/ReactionsViewModel.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/domain/session/room/timeline/ReactionsViewModel.js b/src/domain/session/room/timeline/ReactionsViewModel.js
index b7426b49..83757c13 100644
--- a/src/domain/session/room/timeline/ReactionsViewModel.js
+++ b/src/domain/session/room/timeline/ReactionsViewModel.js
@@ -129,6 +129,12 @@ class ReactionViewModel {
     }
 
     _compare(other) {
+        // the comparator is also used to test for equality, if the comparison returns 0
+        // given that the firstTimestamp isn't set anymore when the last reaction is removed,
+        // the remove event wouldn't be able to find the correct index anymore. So special case equality.
+        if (other === this) {
+            return 0;
+        }
         if (this.count !== other.count) {
             return other.count - this.count;
         } else {