message: Do not panic in flush_dbs in Drop
  Remove expect() and print a message instead. Flushing DBs here should be
  best effort.
diff: @@ -162,8 +162,11 @@ impl PersistentStorage {
  }
  pub fn flush_dbs(&mut self) {
  - self.clog.flush().expect("Failed to flush commit logs");
  - self.kv.flush().expect("Failed to flush database");
  + let clog = self.clog.flush();
  + let kv = self.kv.flush();
  + if clog.is_err() || kv.is_err() {
  + println!("Failed to flush DBs");
  + }
  }
  }
  