Fix use of associative disk array

lib/modules/partition.nix

@@ -1,7 +1,7 @@
 { lib, config, ... }:
   let
     inherit (lib) types mkOption;
-    diskVarName = "myDisk";
+    disksVarName = "myDisk";
     isSwap = partition: builtins.elem partition.type [fs.swap 19];
 
     fs = {
@@ -11,11 +11,6 @@
       fat32 = "fat32";
     };
 
-    diskSelector = ''
-      . ${./../../scripts/Common/Scripts/choose-disk.sh};
-      chooseDisk ${diskVarName} "Which disk do you wish to install the OS on?";
-    '';
-
     mkDiskType = osDisk: types.submodule (
       { config, name, ... }: {
         options = {
@@ -70,7 +65,13 @@
 
         config =
         let
-          diskVar = ''''${${diskVarName}[${config.id}]}'';
+          diskVarName = "${disksVarName}[${config.id}]";
+          diskVar = ''''${${diskVarName}}'';
+
+          diskSelector = ''
+            . ${./../../scripts/Common/Scripts/choose-disk.sh};
+            chooseDisk ${diskVarName} "Which disk do you wish to install the OS on?";
+          '';
 
           partitions = builtins.foldl'
             (list: predicate: lib.lists.sortOn predicate list)
@@ -174,7 +175,7 @@
               ${diskSelector}
             ''
             else ''
-              local ${diskVarName}=${config.devicePath}
+              ${diskVarName}=${config.devicePath}
               ${if osDisk then ''
                 . ${./../../scripts/Common/Scripts/is-truthy.sh}
                 if [ ! -b ${diskVar} ]; then