message: Allow construction zero-sized vector with empty data
diff: @@ -511,6 +511,10 @@ where I: SpIndex,
  return Err(SprsError::NonSortedIndices);
  }
  + if self.dim == 0 && self.indices.len() == 0 && self.data.len() == 0 {
  + return Ok(());
  + }
  +
  let max_ind = self.indices.iter().max().unwrap_or(&I::zero()).index();
  if max_ind >= self.dim {
  panic!("Out of bounds index");
  @@ -1166,4 +1170,9 @@ mod test {
  vec![2., 4., -1., -3., 8., -1.]);
  (a, b, expected_sum)
  }
  +
  + #[test]
  + fn can_construct_zero_sized_vectors() {
  + CsVec::<f64>::new(0, vec![], vec![]);
  + }
  }
  