Categories: Remove not_in_creative_inventory items

`unified_inventory.is_itemdef_listable` already prevents such items
being listed. They are not needed, thus removing them from the
categories in the first place does make sense.

Co-authored-by: SmallJoker <mk939@ymail.com>

api.lua

@@ -187,8 +187,9 @@ minetest.after(0.01, function()
 	-- Remove unknown items from all categories
 	local total_removed = 0
 	for cat_name, cat_def in pairs(ui.registered_category_items) do
-		for itemname, exists in pairs(cat_def) do
-			if exists and not minetest.registered_items[itemname] then
+		for itemname, _ in pairs(cat_def) do
+			local idef = minetest.registered_items[itemname]
+			if not idef then
 				total_removed = total_removed + 1
 				--[[
 				-- For analysis
@@ -197,12 +198,21 @@ minetest.after(0.01, function()
 					.. "'. Reason: item not registered")
 				]]
 				cat_def[itemname] = nil
+			elseif not ui.is_itemdef_listable(idef) then
+				total_removed = total_removed + 1
+				--[[
+				-- For analysis
+				minetest.log("warning", "[unified_inventory] Removed item '"
+					.. itemname .. "' from category '" .. cat_name
+					.. "'. Reason: item is in 'not_in_creative_inventory' group")
+				]]
+				cat_def[itemname] = nil
 			end
 		end
 	end
 	if total_removed > 0 then
 		minetest.log("info", "[unified_inventory] Removed " .. total_removed ..
-			" unknown items from the categories.")
+			" items from the categories.")
 	end
 
 	for _, callback in ipairs(ui.initialized_callbacks) do