add conversation id invalid

Author: kokofixcomputers

src/hugchat/hugchat.py

@@ -741,6 +741,8 @@ def _stream_query(
                         "Model is overloaded, please try again later or switch to another model."
                     )
                 logging.debug(resp.headers)
+                if "Conversation not found" in str(res):
+                    raise exceptions.InvalidConversationIDError("Conversation id invalid")
                 raise exceptions.ChatError(f"Failed to parse response: {res}")
             if break_flag:
                 break