Issue Description
在手动往上翻对话记录时，出现报错，对话记录看不到了
Steps to Reproduce
Expected Behavior
Actual Behavior
Screenshots / Screen Recordings
Operating System
win10 x86_64
Current Qoder Version (Menu → About Qoder → Copy)
版本: 0.2.20
VSCode Version: 1.100.0 (user setup)
提交: 41eefc9d6820b32df7892471dc26c255bf238b67
日期: 2025-12-03T10:05:51.649Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.19045
