refactor: handle missing position file gracefully (#6513)

api/core/helper/position_helper.py

@@ -14,6 +14,9 @@ def get_position_map(folder_path: str, *, file_name: str = "_position.yaml") ->
     :return: a dict with name as key and index as value
     """
     position_file_name = os.path.join(folder_path, file_name)
+    if not position_file_name or not os.path.exists(position_file_name):
+        return {}
+    
     positions = load_yaml_file(position_file_name, ignore_error=True)
     position_map = {}
     index = 0