message: Fix error handling in File::free_space()
diff: @@ -51,7 +51,8 @@ impl File {
  /// Returns the free space in the file in bytes (or 0 if the file handle is invalid).
  pub fn free_space(&self) -> u64 {
  - h5call!(H5Fget_freespace(self.id())).unwrap_or(0) as _
  + let freespace = h5lock!(H5Fget_freespace(self.id()));
  + if freespace < 0 { 0 } else { freespace as _ }
  }
  /// Returns true if the file was opened in a read-only mode.
  