message: Fix pybind empty buffer issue
diff: @@ -42,12 +42,16 @@ def read_calibration_cache(self):
  if os.path.exists(self.cache_file):
  with open(self.cache_file, "rb") as f:
  return f.read()
  + else:
  + return b""
  def write_calibration_cache(self, cache):
  if self.cache_file:
  with open(self.cache_file, "wb") as f:
  f.write(cache)
  + else:
  + return b""
  class DataLoaderCalibrator(object):
  