psd.group_by_id() expects vector index whereas group IDs range 1..n

[gregl83]

Iterate Groups

for group in psd.groups().iter() {
    let group_id = group.id() as usize;
    // first group has value of 1

    let group = psd.group_by_id(group_id);
    // second group returned since vector index of 1 is second element
}

Get Group by ID

/// Get a group by id.
pub fn group_by_id(&self, id: usize) -> Option<&PsdGroup> {
    self.layer_and_mask_information_section
        .groups
        .item_by_idx(id)
}

[chinedufn]

Thanks for opening this!

28 fixes this.