GitHub Copilot restore still shows modifications and breaks on accept

[garretwilson]

1. Request that the LLM modify multiple files and add files as well.
2. Ask the LLM some follow-up questions.
3. Restore the checkpoint on the line before step 1 above.

The files will be reset, the later chat conversation will be removed, and the text of prompt 1 above will be placed in the current prompt input field.

Issue 1: The modified files still have their modified symbol (a filled circle) in their tabs, with the option to "Keep" or "Undo". They were reset—there should be nothing to keep or undo. (This confusing part is related to the #282069, which is similarly confusing.)

4. Go to the chat prompt in the side panel and erase the current prompt input field that was filled.
5. Hit <Ctrl+Enter> to accept all the "changes" (even though there are no real changes at this point).

Expected: The modified symbol disappears from the tabs.

Issue 2: A notification "Cannot read properties of undefined (reading 'toString')" appears in the bottom, right-hand corner of the screen.

Version: 1.107.1 (user setup)
Commit: 994fd12f8d3a5aa16f17d42c041e5809167e845a
Date: 2025-12-17T14:15:14.850Z
Electron: 39.2.3
ElectronBuildId: 12895514
Chromium: 142.0.7444.175
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Windows_NT x64 10.0.26200