[gitlab-ci] yarn is not needed in fact?

1 job for 294-dev-test in 1 minute and 23 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1609
test

00:01:23

 
Name Stage Failure
failed
test Test
copying path '/nix/store/vn70kkifh7xmwi5c9fcrj9fjxsn6rf86-nodejs-14.16.1' from 'https://cache.nixos.org'...
copying path '/nix/store/1gsn2g4f9xz9mbgfyi86bxc8zz849mi6-yarn-1.22.10' from 'https://cache.nixos.org'...
building '/nix/store/9kwxyc2l0kcczl1l711wh1987h2v0sdg-user-environment.drv'...
created 239 symlinks in user environment
$ nix-env -f shell.nix
error: no operation specified
Try 'nix-env --help' for more information.
Cleaning up file based variables
ERROR: Job failed: exit code 1