LS does not handle build directory being deleted while it is running

[GearsDatapacks]

Steps to reproduce:

• Create a new gleam project, and open it with a code editor (I have tested in vscode and zed)
• Open the app_name.gleam file. The LSP works normally
• Run gleam clean in that project
• Save the file in the editor.

The LSP then reports an error:

An error occurred while trying to read this file:

    project/build/packages/gleam_stdlib/gleam.toml

The error message from the file IO library was:

    No such file or directory (os error 2)

This seems to be because it doesn't properly fetch the source files for dependency packages when saving, even if they don't exist. Running gleam check|build|run, or restarting the language server fixes this.

[lpil]

Thank you