When a title has no entry as immediate child, always return 0 as the reading progress

src/library.cr

@@ -212,6 +212,7 @@ class Title
 		page / entry_obj.pages
 	end
 	def load_percetage(username)
+		return 0 if @entries.empty?
 		read_pages = total_pages = 0
 		@entries.each do |e|
 			read_pages += load_progress username, e.title