Force recipes to provide (sub)category

As suggested in CleverRaven#50866, require all recipe definitions to provide a
category and subcategory when loading from JSON.

src/recipe.cpp

@@ -309,8 +309,8 @@ void recipe::load( const JsonObject &jo, const std::string &src )
 
     if( type == "recipe" ) {
 
-        assign( jo, "category", category, strict );
-        assign( jo, "subcategory", subcategory, strict );
+        mandatory( jo, was_loaded, "category", category );
+        mandatory( jo, was_loaded, "subcategory", subcategory );
         assign( jo, "description", description, strict );
         assign( jo, "reversible", reversible, strict );
 
@@ -377,10 +377,10 @@ void recipe::load( const JsonObject &jo, const std::string &src )
         }
     } else if( type == "practice" ) {
         mandatory( jo, false, "name", name_ );
-        assign( jo, "category", category, strict );
-        assign( jo, "subcategory", subcategory, strict );
+        mandatory( jo, was_loaded, "category", category );
+        mandatory( jo, was_loaded, "subcategory", subcategory );
         assign( jo, "description", description, strict );
-        mandatory( jo, false, "practice_data", practice_data );
+        mandatory( jo, was_loaded, "practice_data", practice_data );
 
         if( jo.has_member( "byproducts" ) ) {
             byproducts.clear();

src/recipe.h

@@ -107,6 +107,7 @@ class recipe
             return result_;
         }
 
+        bool was_loaded = false;
         bool obsolete = false;
 
         std::string category;

src/recipe_dictionary.cpp

@@ -404,6 +404,7 @@ recipe &recipe_dictionary::load( const JsonObject &jo, const std::string &src,
     }
 
     r.load( jo, src );
+    r.was_loaded = true;
 
     return out[ r.ident() ] = std::move( r );
 }