editor: Fix panic when full width crease is wrapped (#31960)

Closes #31919

Release Notes:

- Fixed a panic that could sometimes occur when the agent panel was too
narrow and contained context included via `@`.

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Co-authored-by: Antonio <antonio@zed.dev>
Co-authored-by: Antonio Scandurra <me@as-cii.com>
27d3da678cBennet Bo Fenner committed on 6/3/2025, 8:59:27 PM· committed by GitHubparent03357f3
2 files changedLine totals unavailable