100% CPU when --wait-after-command process exits

[mitchellh]

Reproduction:

1. zig build run -Dapp-runtime=glfw -- --wait-after-command=true
2. Type exit in the launched window
3. See CPU usage

There was a previously attempted fix at #4171 but it caused #4882.

I suspect there is some relation to #4554 as well in the sense that all of our process management there is suspicious.

[AvicennaJr]

Could this be related to this scenario:

• I open the terminal
• I split the terminal (Down or Right)
• I try to exit the first pane
• It hangs

You can see the video below to understand better:

ghostty_bug-2025-01-10_11.35.07.mp4