From 2f78a02db98997a4ea0a07f1a645820eb542fb14 Mon Sep 17 00:00:00 2001
From: Hakan Kosdag <hakankosdag@gmail.com>
Date: Fri, 28 Feb 2025 05:48:17 +0300
Subject: [PATCH 1/2] fix: add mergedData length check

---
 src/List.tsx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/List.tsx b/src/List.tsx
index 9afe3bfb..10a52f49 100644
--- a/src/List.tsx
+++ b/src/List.tsx
@@ -277,7 +277,7 @@ export function RawList<T>(props: ListProps<T>, ref: React.Ref<ListRef>) {
   // Let's sync scroll top to avoid jump
   React.useLayoutEffect(() => {
     const changedRecord = heights.getRecord();
-    if (changedRecord.size === 1) {
+    if (changedRecord.size === 1 && mergedData.length > 0) {
       const recordKey = Array.from(changedRecord)[0];
       const startIndexKey = getKey(mergedData[start]);
       if (startIndexKey === recordKey) {

From eb4f6e5ca313354cb37bf44c0a030a03fab10a01 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=BA=8C=E8=B4=A7=E6=9C=BA=E5=99=A8=E4=BA=BA?=
 <smith3816@gmail.com>
Date: Fri, 28 Feb 2025 14:35:34 +0800
Subject: [PATCH 2/2] chore: check first

---
 src/List.tsx | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/List.tsx b/src/List.tsx
index 10a52f49..0da61f32 100644
--- a/src/List.tsx
+++ b/src/List.tsx
@@ -277,15 +277,19 @@ export function RawList<T>(props: ListProps<T>, ref: React.Ref<ListRef>) {
   // Let's sync scroll top to avoid jump
   React.useLayoutEffect(() => {
     const changedRecord = heights.getRecord();
-    if (changedRecord.size === 1 && mergedData.length > 0) {
+    if (changedRecord.size === 1) {
       const recordKey = Array.from(changedRecord)[0];
-      const startIndexKey = getKey(mergedData[start]);
-      if (startIndexKey === recordKey) {
-        const realStartHeight = heights.get(recordKey);
-        const diffHeight = realStartHeight - itemHeight;
-        syncScrollTop((ori) => {
-          return ori + diffHeight;
-        });
+      // Quick switch data may cause `start` not in `mergedData` anymore
+      const startItem = mergedData[start];
+      if (startItem) {
+        const startIndexKey = getKey(startItem);
+        if (startIndexKey === recordKey) {
+          const realStartHeight = heights.get(recordKey);
+          const diffHeight = realStartHeight - itemHeight;
+          syncScrollTop((ori) => {
+            return ori + diffHeight;
+          });
+        }
       }
     }