this derivation will be built:
  /nix/store/lixky83xxpnhfm4lq0shlqf3ipwkgdy4-spec-nixfmt.drv
building '/nix/store/lixky83xxpnhfm4lq0shlqf3ipwkgdy4-spec-nixfmt.drv' on 'ssh-ng://customer@mac02.m.ntd.one'
building '/nix/store/lixky83xxpnhfm4lq0shlqf3ipwkgdy4-spec-nixfmt.drv'
spec-nixfmt> invalid/a.nix:1:7:
spec-nixfmt>   |
spec-nixfmt> 1 | { a = ;
spec-nixfmt>   |       ^^
spec-nixfmt> unexpected ";<newline>"
spec-nixfmt> expecting expression
spec-nixfmt> 

upload niks3: ok