sub _store_workbook {
    ...
    my $tempdir  = File::Temp->newdir( DIR => $self->{_tempdir} );
    print "tempdir='$tempdir'\n"; # debug
    if( ! -d $tempdir ){ croak "$tempdir was not created" } # debug
        my $mode = (stat($tempdir))[2];
        printf "Permissions are %04o\n", $mode & 07777;
    
    ...
    $packager->_set_package_dir( $tempdir );
    $packager->_create_package();
    ...
}