Fix panic when re-editing old message with creases (#32017)

Co-authored-by: Cole Miller <m@cole-miller.net>

Release Notes:

- agent: Fixed a panic when re-editing old messages

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Co-authored-by: Cole Miller <m@cole-miller.net>
Co-authored-by: Cole Miller <cole@zed.dev>
03357f3f7bConrad Irwin committed on 6/3/2025, 8:56:18 PM· committed by GitHubparent4aabba6
3 files changedLine totals unavailable