gitea: bugfix: add check for empty file for secrets

[asbachb]

There are some cases were the files are present but not filled with secrets. In these cases the service fails to startup.

This fixes #175967

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.11 Release Notes (or backporting 22.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[SuperSandro2000]

Wouldn't it be a good idea to log something if the secret is empty instead of silently ignoring it?

[asbachb]

Wouldn't it be a good idea to log something if the secret is empty instead of silently ignoring it?

From my understanding the idea is to generate secrets if they're not provided.

The problem with current behavior just pops up when you had a previous installation of gitea.