From 5bb03eb8f4390c42e32e0227bb2b2fbaaaad1eb2 Mon Sep 17 00:00:00 2001
From: Jinjing <6427696+AmethystLiang@users.noreply.github.com>
Date: Mon, 13 Apr 2026 23:31:50 -0700
Subject: [PATCH] fix: guard WorktreeList getItemKey against stale virtualizer
 cache entries (#625)

When rows shrink (group collapse, worktree removal) while PR/issue data
arrives asynchronously, the virtualizer's elementsCache can hold stale
entries whose data-index exceeds the new rows length. measureElement
calls getItemKey for those stale indices, causing "Cannot read properties
of undefined (reading 'type')". Add a null guard matching the pattern
already used by FileExplorer and Search virtualizers.
---
 src/renderer/src/components/sidebar/WorktreeList.tsx | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/renderer/src/components/sidebar/WorktreeList.tsx b/src/renderer/src/components/sidebar/WorktreeList.tsx
index f3ac586a9..33612f083 100644
--- a/src/renderer/src/components/sidebar/WorktreeList.tsx
+++ b/src/renderer/src/components/sidebar/WorktreeList.tsx
@@ -323,6 +323,14 @@ const WorktreeList = React.memo(function WorktreeList() {
     gap: 6,
     getItemKey: (index) => {
       const row = rows[index]
+      // Why: when rows shrink (group collapse, worktree removal) the
+      // virtualizer's elementsCache can still hold stale entries whose
+      // data-index exceeds the new rows length. measureElement calls
+      // getItemKey for those stale indices, so we need a fallback to
+      // avoid "Cannot read properties of undefined (reading 'type')".
+      if (!row) {
+        return `__stale_${index}`
+      }
       return row.type === 'header' ? `hdr:${row.key}` : `wt:${row.worktree.id}`
     }
   })