No need for ourpkgs here.

nixos/modules/monitoring/exporters/tahoe.nix

@@ -7,7 +7,7 @@
 #
 # See https://nixos.org/manual/nixos/stable/#module-services-prometheus-exporters
 
-{ config, options, lib, ourpkgs, pkgs, ... }:
+{ config, options, lib, pkgs, ... }:
 
 let
   cfg = config.services.private-storage.monitoring.tahoe;