lib/options: Throw error for options without a type

Makes all options rendered in the manual throw an error if they don't
have a type specified.

This is a follow-up to #76184

Co-Authored-By: Silvan Mosberger <contact@infinisil.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/nixos/doc/manual/from_md/development/option-declarations.section.xml b/nixos/doc/manual/from_md/development/option-declarations.section.xml
index 0eeffae628e..c7b62192158 100644
--- a/nixos/doc/manual/from_md/development/option-declarations.section.xml
+++ b/nixos/doc/manual/from_md/development/option-declarations.section.xml
@@ -38,9 +38,11 @@ options = {
       <listitem>
         <para>
           The type of the option (see
-          <xref linkend="sec-option-types" />). It may be omitted, but
-          that’s not advisable since it may lead to errors that are hard
-          to diagnose.
+          <xref linkend="sec-option-types" />). This argument is
+          mandatory for nixpkgs modules. Setting this is highly
+          recommended for the sake of documentation and type checking.
+          In case it is not set, a fallback type with unspecified
+          behavior is used.
         </para>
       </listitem>
     </varlistentry>