Use vim.system instead of io.popen

[benjosua]

Replace io.popen() with vim.system() for safer command execution and better error handling.

[Copilot]

Pull request overview

This pull request replaces the use of io.popen with vim.system throughout the codebase for executing external commands. This change improves security by avoiding shell injection risks, provides better error handling, and aligns with modern Neovim API best practices.

Changes:

• Replaced io.popen with vim.system in git diff execution for safer command handling
• Removed the exec helper function and converted all Unix process discovery commands to use vim.system
• Updated error handling in Windows PowerShell execution and Unix process walking to handle command failures more gracefully

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
lua/opencode/context.lua	Updated git_diff() to use vim.system instead of io.popen with improved error handling
lua/opencode/cli/server.lua	Removed exec() helper; converted get_processes_unix(), is_descendant_of_neovim() to use vim.system; adjusted PowerShell error handling in get_processes_windows()

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[NickvanDyke]

Nice, tyvm for this!

Now that we have more information about the result, could you check for a non-zero codes and error(<cmd> failed with <code>\nstderr:\n<stderr>) in that case? Just to save us from some silent failure headaches in the future 😀