fix(plan): add return type hint and handle non-list data input

csst_dfs_client/plan.py

@@ -85,7 +85,7 @@ def find_by_opid(opid: str) -> Result:
     """
     return request.get(f"/api/plan/{opid}")
 
-def load_file(local_file: Union[IO, str, list]):
+def load_file(local_file: Union[IO, str, list]) -> list:
     """
     将本地json文件、json数据流或json数据列表写入DFS中。
 
@@ -108,7 +108,8 @@ def load_file(local_file: Union[IO, str, list]):
         raise ValueError("Unsupported type for local_file")
 
     if not isinstance(data, list):
-        raise ValueError("Data must be a list of JSON objects")    
+        raise ValueError("Data must be a list of JSON objects")
+    return data 
 def write_file(local_file: Union[IO, str, list]) -> Result:
     """
     将本地json文件、json数据流或json数据列表写入DFS中。