From 23b1fb8984461e5a62739298186de3bc1228f841 Mon Sep 17 00:00:00 2001
From: Cory LaViska <cory@abeautifulsite.net>
Date: Wed, 12 Jul 2023 11:19:55 -0400
Subject: [PATCH] unset last focused item; #1436

---
 src/components/tree/tree.ts | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/components/tree/tree.ts b/src/components/tree/tree.ts
index b0dc010b..7522bc10 100644
--- a/src/components/tree/tree.ts
+++ b/src/components/tree/tree.ts
@@ -87,7 +87,7 @@ export default class SlTree extends ShoelaceElement {
   // A collection of all the items in the tree, in the order they appear. The collection is live, meaning it is
   // automatically updated when the underlying document is changed.
   //
-  private lastFocusedItem: SlTreeItem;
+  private lastFocusedItem: SlTreeItem | null;
   private readonly localize = new LocalizeController(this);
   private mutationObserver: MutationObserver;
   private clickTarget: SlTreeItem | null = null;
@@ -159,8 +159,13 @@ export default class SlTree extends ShoelaceElement {
   private handleTreeChanged = (mutations: MutationRecord[]) => {
     for (const mutation of mutations) {
       const addedNodes: SlTreeItem[] = [...mutation.addedNodes].filter(SlTreeItem.isTreeItem) as SlTreeItem[];
+      const removedNodes = [...mutation.removedNodes].filter(SlTreeItem.isTreeItem) as SlTreeItem[];
 
       addedNodes.forEach(this.initTreeItem);
+
+      if (this.lastFocusedItem && removedNodes.includes(this.lastFocusedItem)) {
+        this.lastFocusedItem = null;
+      }
     }
   };