From 6a389fd15a1d677daa47c090c06ad4ded47aec75 Mon Sep 17 00:00:00 2001
From: Jarek Radosz <jradosz@gmail.com>
Date: Wed, 30 Nov 2022 16:55:30 +0100
Subject: [PATCH] FIX: ScrollingPostStream regressed in #15313 (#18584)

regression commit: bec76f937cfb7564ff3c63c57e3372ba99378371

In case when the user navigates away between async actions that code would error out on a missing element. This adds a simple sanity check.
---
 .../app/components/scrolling-post-stream.js   | 27 ++++++++++---------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/app/assets/javascripts/discourse/app/components/scrolling-post-stream.js b/app/assets/javascripts/discourse/app/components/scrolling-post-stream.js
index 1b640951efc..901005e0866 100644
--- a/app/assets/javascripts/discourse/app/components/scrolling-post-stream.js
+++ b/app/assets/javascripts/discourse/app/components/scrolling-post-stream.js
@@ -190,20 +190,21 @@ export default MountWidget.extend({
           refresh(() => {
             const refreshedElem = document.getElementById(elemId);
 
-            // Quickly going back might mean the element is destroyed
-            const position = domUtils.position(refreshedElem);
-            if (position && position.top) {
-              let whereY = position.top - distToElement;
-              document.documentElement.scroll({ top: whereY, left: 0 });
-
-              // This seems weird, but somewhat infrequently a rerender
-              // will cause the browser to scroll to the top of the document
-              // in Chrome. This makes sure the scroll works correctly if that
-              // happens.
-              schedule("afterRender", () => {
-                document.documentElement.scroll({ top: whereY, left: 0 });
-              });
+            if (!refreshedElem) {
+              return;
             }
+
+            const position = domUtils.position(refreshedElem);
+            const top = position.top - distToElement;
+            document.documentElement.scroll({ top, left: 0 });
+
+            // This seems weird, but somewhat infrequently a rerender
+            // will cause the browser to scroll to the top of the document
+            // in Chrome. This makes sure the scroll works correctly if that
+            // happens.
+            schedule("afterRender", () => {
+              document.documentElement.scroll({ top, left: 0 });
+            });
           });
         };
         this.topVisibleChanged({