types/description: add support for make_description<void>

types/description.hpp

@@ -70,11 +70,18 @@ namespace cruft::types {
     constexpr description
     make_description (void) noexcept
     {
+        if constexpr (std::is_void_v<T>) {
+            return {
+                .category = category::NONE,
+                .width    = 0,
+            };
+        } else {
             return {
                 .category = category_traits_v<T>,
                 .width = sizeof (T)
             };
         }
+    }
 
 
     /// Call a functor with the supplied arguments and a type_tag for the