Handle to background job is dropped if `$env.PROMPT` closure is exited prematurely

Bug report form

• I have done a basic search of the issue tracker to find any existing issues that are similar.
• I have checked that my version is at least the latest stable release available via my installation method.

Describe the bug

$ ff

Job 102 is re-frozen
q^C^[Error: nu::shell::error

  × Operation interrupted
   ╭─[/Users/mkatychev/.config/nu/prompt.nu:6:16]
 5 │ ]: int -> oneof<string, nothing> {
 6 │     let icon = match $in {
   ·                ──┬──
   ·                  ╰── This operation was interrupted
 7 │         1 => $one
   ╰────

~/Documents/rust/nushell-ci>

• prompt.nu code section

• export def ff

How to reproduce

1. Have $env.PROMPT defined as a closure that is rather expensive, in this case calling gstat on a big repo in a big repo such as https://github.com/nushell/nushell/

• the larger the repo (commits and submodules) the better https://github.com/github-linguist/linguist/ triggers more reliably

1. Start an CPU intensive task in another shell or session (like a release build of nushell with all features!).
2. have background jobs frozen in a nu session and change directories rapidly to make a lot of $env.PROMPT calls
3. ^C before $env.PROMPT_COMMAND has finished

Expected behavior

I expect errors to happen during CPU scheduling but not to have said errors result in dropping all references to background jobs

Configuration