feat(diagnostics): split error and shutdown messages

libs/kaptan-config-mavlink/src/protocol.rs

@@ -180,9 +180,10 @@ mod tests {
         let record = hub.peek().expect("rejection is retained");
         assert_eq!(record.channel(), RecordChannel::Error);
         assert_eq!(
-            record.message().as_str(),
+            record.error_path().unwrap().as_str(),
             "kaptan_config_mavlink::protocol::ProtocolError::BadState"
         );
+        assert!(record.additional_information().unwrap().is_empty());
 
         let accepted = ConfigReply {
             result: ResultKind::Accepted,