Panic occurs when rotation happens after log files are deleted

[bfdyanshe]

at ftlog-0.2.15/src/appender/file.rs:442

       // rotate file
                self.file = BufWriter::new(
                    OpenOptions::new()
                        .create(true)
                        .append(true)
                        .open(path)
                        .unwrap(),
                );