message: Fix logic error in _build_vrt
diff: @@ -79,7 +79,7 @@ pub fn build_vrt<D: Borrow<Dataset>>(
  fn _build_vrt(dest: Option<&Path>, datasets: &[&Dataset], args: Vec<String>) -> Result<Dataset> {
  // Convert dest to CString
  let dest = dest.map(_path_to_c_string).transpose()?;
  - let c_dest = dest.map(|x| x.as_ptr()).unwrap_or(null());
  + let c_dest = dest.as_ref().map(|x| x.as_ptr()).unwrap_or(null());
  let result = unsafe {
  let options = BuildVRTOptions::new(args)?;
  