This was a simple mistake. Look here:

for my $col(0..4)
    {
    my $key=$worksheet->get_cell(0,$col)->value;
    my $cell=$worksheet->get_cell($row,$col);
    next unless $cell;
    my $value=$cell->value();
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The blank cells in Garry's row are causing the error, meaning that your 'next unless $cell' statement is not skipping the empty cells. Maybe try:

for my $col(0..4)
    {
    my $key=$worksheet->get_cell(0,$col)->value;
    my $cell=$worksheet->get_cell($row,$col);
    unless($cell){ # Null value }
    else{
       my $value=$cell->value();
       ...
    }
[download]

I tested this and it worked for me.