some minor fixes for python client

src/controller.rs

@@ -28,12 +28,18 @@ impl ExperimentController {
     pub fn perform_operation(&mut self) {
         match self.composite_request_rx.try_recv() {
             Ok(msg) => match msg.message {
-                CompositeRequest::Hk(_) => todo!(),
+                CompositeRequest::Hk(_) => {
+                    log::warn!("hk request handling unimplemented")
+                }
                 CompositeRequest::Action(action_req) => {
                     self.handle_action_request(msg.requestor_info, action_req);
                 }
             },
-            Err(_) => todo!(),
+            Err(e) => {
+                if e != mpsc::TryRecvError::Empty {
+                    log::error!("composite request rx error: {:?}", e);
+                }
+            }
         }
         self.check_stop_file();
     }