fix(nodev); Set device default to fstype config

The value for device is copied into the SOURCE column of findmnt.
By default this is "none". The mount and unmount scripts
branch on SOURCE=fsType specifically, and the existence of "none"
in the SOURCE column causes wrong branches to be executed.
For a list of special filesystems, the default value "none"
is replaced by the value for fsType.

Author: Bert-Proesmans

lib/types/nodev.nix

@@ -6,6 +6,17 @@
   rootMountPoint,
   ...
 }:
+let
+  # REF; nixos/modules/tasks/filesystems.nix
+  specialFSTypes = [
+    "proc"
+    "sysfs"
+    "tmpfs"
+    "ramfs"
+    "devtmpfs"
+    "devpts"
+  ];
+in
 {
   options = {
     type = lib.mkOption {
@@ -86,4 +97,7 @@
       description = "Packages";
     };
   };
+  config = {
+    device = lib.mkIf (lib.elem config.fsType specialFSTypes) (lib.mkDefault config.fsType);
+  };
 }