message: Internal fix on converter.
diff: @@ -225,7 +225,8 @@ PyObject* CalibrationWrapper::SetTensor(int index, PyObject* value) {
  for (int j = 0; j < PyArray_NDIM(array); j++) {
  // Ensure the calibration data input shape is the same as the model input
  // shape unless the dimension is unknown.
  - if (tensor->dims_signature->size == tensor->dims->size &&
  + if (tensor->dims_signature != nullptr &&
  + tensor->dims_signature->size == tensor->dims->size &&
  tensor->dims_signature->data[j] == -1) {
  has_unknown_dims = true;
  } else if (tensor->dims->data[j] != PyArray_SHAPE(array)[j]) {
  