nixos/vaultwarden: use lib.concatMapAttrs

  # we can only check for values consistently after converting them to their corresponding environment variable name.

  configEnv =

    let

      configEnv = listToAttrs (concatLists (mapAttrsToList (name: value:

        if value != null then [ (nameValuePair (nameToEnvVar name) (if isBool value then boolToString value else toString value)) ] else []

      ) cfg.config));

      configEnv = concatMapAttrs (name: value: optionalAttrs (value != null) {

        ${nameToEnvVar name} = if isBool value then boolToString value else toString value;

      }) cfg.config;

    in { DATA_FOLDER = "/var/lib/bitwarden_rs"; } // optionalAttrs (!(configEnv ? WEB_VAULT_ENABLED) || configEnv.WEB_VAULT_ENABLED == "true") {

      WEB_VAULT_FOLDER = "${cfg.webVaultPackage}/share/vaultwarden/vault";

    } // configEnv;