Secret files are not available during preStart

when using the secretFile option in go-neb: https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/services/networking/go-neb.nix#L20

I get the following error:

n 28 14:49:09 matrix-00.mainnet.kuutamo.computer 8rdynbb9ws97hfv52w96125j1nnamwf7-pre-start[32876]: /nix/store/8rdynbb9ws97hfv52w96125j1nnamwf7-pre-start: line 3: /tmp/detsys-vault/go-neb-secrets: No such file or directory