Fish support script errors with 'return' outside of function definition

[isomorpheme]

Describe the bug

I re-ran the latest install script to get the new scripts for Fish installed (#7014, #7040), but it looks like the script sourced by /etc/fish/conf.d/nix.fish crashes on my system's version of Fish.

Steps To Reproduce

1. Install (multi-user) Nix 2.11.1 with the usual sh <(curl -L https://nixos.org/nix/install) --daemon (I did this from within Fish so I ran sh (curl -L https://nixos.org/nix/install | psub) --daemon instead.)
2. Open a new terminal running Fish.
3. Error:

   /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.fish (line 3): 'return' outside of function definition
     return
     ^
   from sourcing file /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.fish
       called on line 4 of file /etc/fish/conf.d/nix.fish
   from sourcing file /etc/fish/conf.d/nix.fish
       called on line 253 of file /usr/share/fish/config.fish
   from sourcing file /usr/share/fish/config.fish
       called during startup
   .: Error while reading file “/nix/var/nix/profiles/default/etc/profile.d/nix-daemon.fish”
   

   (And nix-env etc. aren't available.)

Expected behavior

No error, and the right environment variables are loaded for Nix to work from Fish.

nix-env --version output

$ nix-env --version
nix-env (Nix) 2.11.1

(Ran from bash instead of fish.)

Additional context

$ fish --version
fish, version 3.3.1

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 22.04.1 LTS
Release:	22.04
Codename:	jammy

[isomorpheme]

I'm guesing the problem is that older/newer versions of Fish than the one I'm using do allow return outside of functions, and that the fix is probably as simple as using exit instead.

Edit: yep, the option to use return outside of functions was added in 3.4: https://fishshell.com/docs/current/relnotes.html#id3

[edolstra]

I think this is fixed in #7105.

[isomorpheme]

Oh, I should have thought to look through PRs as well. Thanks! I'll close this then.