code: public function getByteSize(): int
      {
          if ($this->test(\sndsgd\Fs::READABLE) !== true) {
              $this->error = "failed to stat filesize; {$this->error}";
              return -1;
          }
          $bytes = @filesize($this->path);
          if ($bytes === false) {
              $this->setError("failed to stat filesize for '{$this->path}'");
              return -1;
          }
          return $bytes;
      }
docs: Get the byte size of the file
  
  @return int `-1` if the size could not be determined