GUI: crash on reset DetectorScene

void MaskHandler::clearGraphicMaskItems(ohkl::sptrDataSet dataset)
{
    auto imasks = dataset->masks();
    for (auto& m : imasks) {
        if (!m)
            return;
        delete getGraphicItem(dataset, m);
        _mask_collection_map[dataset].erase(m);
    }
}

The crash occurs on the delete line