Output a warning if attempting to load the OAI_CONFIG_LIST from a file, but the file is not found. (#174)

Author: afourney

autogen/oai/openai_utils.py

@@ -237,10 +237,12 @@ def config_list_from_json(
     if json_str:
         config_list = json.loads(json_str)
     else:
+        config_list_path = os.path.join(file_location, env_or_file)
         try:
-            with open(os.path.join(file_location, env_or_file)) as json_file:
+            with open(config_list_path) as json_file:
                 config_list = json.load(json_file)
         except FileNotFoundError:
+            logging.warning(f"The specified config_list file '{config_list_path}' does not exist.")
             return []
     return filter_config(config_list, filter_dict)