Move the script to the fileSystems module

lib/modules/fileSystems.nix

@@ -1,6 +1,7 @@
 { lib, config, ... }:
 let
   inherit (lib) types mkOption;
+  cfg = config.valhalla.fileSystems;
 in {
   imports = [
     ./partition/disks.nix
@@ -20,7 +21,26 @@ in {
   config = {
     valhalla = {
       fileSystems = {
-        script = config.valhalla.fileSystems.diskSetup.script;
+        script = let
+          disks = (builtins.attrValues cfg.diskSetup.disks);
+        in ''
+          #!/bin/bash
+          set -o errexit
+          ${cfg.diskSetup.scripts.init}
+          ${lib.strings.concatLines (lib.optionals ((builtins.length disks) > 0) [
+            ''echo "$(tput setaf 3)=== WARNING ====$(tput sgr0)"''
+            (''echo "Continuing this script will alter the partitions of ''
+              + (lib.strings.concatStringsSep ", " (builtins.map (_: "${_.deviceVariable}") (lib.lists.init disks)))
+              + (if (builtins.length disks) > 1 then " and " else "") + (lib.lists.last disks).deviceVariable + ''"'')
+            ''
+              if ! fish ${./partition/confirm.fish} "Are you sure you want to continue?" "n"; then
+                exit 1
+              fi
+            ''
+          ])}
+          ${cfg.diskSetup.scripts.partition}
+          ${cfg.diskSetup.scripts.mount}
+        '';
       };
     };
   };

lib/modules/partition/disks.nix

@@ -314,35 +314,6 @@ in
               description = "The script for mounting the partitioned disks.";
             };
           };
-
-          script = mkOption {
-            type = types.str;
-            description = "The script for partitioning the system's disks.";
-            default =
-              let
-                cfg = config.valhalla.fileSystems.diskSetup;
-                inherit (cfg) scripts;
-                disks = (builtins.attrValues cfg.disks);
-              in
-              ''
-                #!/bin/bash
-                set -o errexit
-                ${scripts.init}
-                ${lib.strings.concatLines (lib.optionals ((builtins.length disks) > 0) [
-                  ''echo "$(tput setaf 3)==== WARNING ====$(tput sgr0)"''
-                  (''echo "Continuing this script will alter the partitions of ''
-                    + (lib.strings.concatStringsSep ", " (builtins.map (_: "${_.deviceVariable}") (lib.lists.init disks)))
-                    + (if (builtins.length disks) > 1 then " and " else "") + (lib.lists.last disks).deviceVariable + ''"'')
-                  ''
-                    if ! fish ${./confirm.fish} "Are you sure you want to continue?" "n"; then
-                      exit 1
-                    fi
-                  ''
-                ])}
-                ${scripts.partition}
-                ${scripts.mount}
-              '';
-          };
         };
       };
     };