fix for chatinterface not being visible post successful PDF upload

app.py

@@ -58,7 +58,7 @@ class PDFChatbot:
 
             return (
                 gr.update(interactive=False),
-                gr.update(visible=True)
+                gr.Group.update(visible=True)
             )
         except Exception as e:
             if os.path.exists(self.state.vector_store_path):
@@ -66,7 +66,7 @@ class PDFChatbot:
             gr.Error(f"An error occurred: {str(e)}")
             return (
                 gr.update(interactive=True),
-                gr.update(visible=False)
+                gr.Group.update(visible=False)
             )
 
     def chat_with_pdf(self, message, history):