Add missing return

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

Author: JinHai-CN

agent/component/base.py

@@ -514,14 +514,15 @@ def get_component_name(self, cpn_id) -> str:
     def get_param(self, name):
         if hasattr(self._param, name):
             return getattr(self._param, name)
+        return None
 
     def debug(self, **kwargs):
         return self._invoke(**kwargs)
 
     def get_parent(self) -> Union[object, None]:
         pid = self._canvas.get_component(self._id).get("parent_id")
         if not pid:
-            return
+            return None
         return self._canvas.get_component(pid)["obj"]
 
     def get_upstream(self) -> List[str]:
@@ -546,7 +547,7 @@ def repl(_match, val=v):
 
     def exception_handler(self):
         if not self._param.exception_method:
-            return
+            return None
         return {
             "goto": self._param.exception_goto,
             "default_value": self._param.exception_default_value