From 9d2db5a648f545f87db36e594621ffe121edb652 Mon Sep 17 00:00:00 2001
From: Your Name <aa@bb.com>
Date: Sun, 6 Sep 2026 00:46:37 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E8=BD=AC=E5=8F=91/=E5=88=87?=
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componentDidUpdate 的 initMessage 分支直接访问 this.messageEditArea
未判空，而输入框在 noInput（转发中）或 disabled（ACS未解析完）时会
被卸载——此时 initMessage（草稿/编辑内容）一变化就会解引用 null，
无 error boundary 兜底，整个应用白屏。

第十轮最小粒度测试 Ch3-4（实测复现2次）与 Ch8（同一处代码路径独立
命中）各自发现同一个bug。

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
---
 src/widgets/send-message.jsx | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/widgets/send-message.jsx b/src/widgets/send-message.jsx
index f5d5b0c2..aac712a6 100644
--- a/src/widgets/send-message.jsx
+++ b/src/widgets/send-message.jsx
@@ -228,9 +228,14 @@ class SendMessage extends React.PureComponent {
     } else if (prevProps.initMessage != this.props.initMessage) {
       const msg = this.props.initMessage || '';
       this.setState({message: msg}, _ => {
-        // If there is text, scroll to bottom and set caret to the end.
-        this.messageEditArea.scrollTop = this.messageEditArea.scrollHeight;
-        this.messageEditArea.setSelectionRange(msg.length, msg.length);
+        // messageEditArea can be null here: initMessage (draft/edit content) can change while the
+        // textarea itself is unmounted, e.g. noInput during an active forward, or disabled while
+        // ACS is still resolving right after a topic switch.
+        if (this.messageEditArea) {
+          // If there is text, scroll to bottom and set caret to the end.
+          this.messageEditArea.scrollTop = this.messageEditArea.scrollHeight;
+          this.messageEditArea.setSelectionRange(msg.length, msg.length);
+        }
       });
     }
     if (prevProps.reply != this.props.reply) {