fix(os_symphony_evaluation) (#410)

* fix(os_symphony)

* Update desktop_env_os_symphony.py

* fix(os_symphony_desktop)

* fix(os_symphony_start)

* Add docstring to run_multienv_os_symphony.py

Added documentation header for the evaluation script.

desktop_env/desktop_env_os_symphony.py

@@ -333,6 +333,8 @@ class DesktopEnv(gym.Env):
 
     def _set_evaluator_info(self, task_config: Dict[str, Any]):
         """Set evaluator information from task config"""
+        if "evaluator" not in task_config:
+            return
         # evaluator dict
         # func -> metric function string, or list of metric function strings
         # conj -> conjunction of multiple metrics if func is a list with length > 1, "and"/"or"