Bug in nix completion for fish shell

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Hi!

I use NixOS with a flake-based configuration.

nix --version
nix (Nix) 2.13.3

When trying to use tab completions for nix subcommands(such as nix search) in my fish shell environment, this error prints out(slowly) instead:

nix: src/libutil/args.cc:32: void nix::Completions::add(std::string, std::string): Assertion `description.find('\n') == std::string::npos' failed.
nix: src/libutil/args.cc:32: void nix::Completions::add(std::string, std::string): Assertion `description.find('\n') == std::string::npos' failed.
test: Missing argument at index 3
= filenames
            ^
/run/current-system/sw/share/fish/vendor_completions.d/nix.fish (line 22):
  test $response[1] = 'filenames'
  ^
in function '_nix_accepts_files'
in command substitution

Anyone encountered something like this?

Thanks for any hint!