programs.khal: Simplify calendar setup (#5073)

* programs.khal: fix build failure due to null value

* calendar: allow null value for primaryCollection

* calendar / programs.khal: set default values to avoid common errors

modules/accounts/calendar.nix

@@ -18,12 +18,13 @@ let
 
         type = mkOption {
           type = types.enum [ "filesystem" "singlefile" ];
+          default = "filesystem";
           description = "The type of the storage.";
         };
 
         fileExt = mkOption {
           type = types.nullOr types.str;
-          default = null;
+          default = ".ics";
           description = "The file extension to use.";
         };
 
@@ -98,7 +99,8 @@ let
       };
 
       primaryCollection = mkOption {
-        type = types.str;
+        type = types.nullOr types.str;
+        default = null;
         description = ''
           The primary collection of the account. Required when an
           account has multiple collections.
@@ -106,8 +108,8 @@ let
       };
 
       local = mkOption {
-        type = types.nullOr (localModule name);
-        default = null;
+        type = localModule name;
+        default = { };
         description = ''
           Local configuration for the calendar.
         '';
@@ -129,6 +131,7 @@ in {
   options.accounts.calendar = {
     basePath = mkOption {
       type = types.str;
+      example = ".calendar";
       apply = p:
         if hasPrefix "/" p then p else "${config.home.homeDirectory}/${p}";
       description = ''

modules/programs/khal-calendar-accounts.nix

@@ -5,8 +5,8 @@ with lib;
 {
   options.khal = {
     type = mkOption {
-      type = types.nullOr (types.enum [ "calendar" "discover" ]);
-      default = null;
+      type = types.enum [ "calendar" "discover" ];
+      default = "calendar";
       description = ''
         Either a single calendar (calendar which is the default) or a directory with multiple calendars (discover).
       '';