gpui: Avoid dereferencing null pointer (#30579)

as
[comments](https://github.com/zed-industries/zed/pull/24545#issuecomment-2872833658),
I really don't known why, But IMO, add this code is not harm.

If you think this is not necessary, can close.

Release Notes:

- N/A
b2fc4064c0CharlesChen0823 committed on 5/15/2025, 7:50:58 AM· committed by GitHubparentbba3db9
1 file changedLine totals unavailable