fixed odd orders

src/tree.py

@@ -101,6 +101,7 @@ class TreeWalker:
                     section_title = list(section_node.keys())[0]
                     full_path = os.path.join(chapter_path, f"{index + 1}.{section_title}")
                     if os.path.isdir(full_path):
+                        self.check_section_keywords(full_path)
                         self.ensure_exercises(full_path)
 
         tree_path = os.path.join(self.root, "tree.json")
@@ -309,3 +310,9 @@ class TreeWalker:
                 dump_json(full_name, exercise, True, True)
             else:
                 id_set.add(exercise["exercise_id"])
+
+    def check_section_keywords(self, full_path):
+        config = self.ensure_section_config(full_path)
+        if not config.get("keywords", []):
+            self.logger.error(f"节点 [{full_path}] 的关键字为空，请修改配置文件写入关键字")
+            sys.exit(1)