Fix lazy init websurfer (#4178)

* lazy init set

* format

python/packages/autogen-ext/src/autogen_ext/agents/web_surfer/_multimodal_web_surfer.py

@@ -265,6 +265,7 @@ class MultimodalWebSurfer(BaseChatAgent):
 
         # Prepare the debug directory -- which stores the screenshots generated throughout the process
         await self._set_debug_dir(self.debug_dir)
+        self.did_lazy_init = True
 
     async def _set_debug_dir(self, debug_dir: str | None) -> None:
         assert self._page is not None