# I changed this
$row->[15] = '';
($row->[15]) = $row->[5] =~ /(#[^ ]+)/;

# to this and it does what I want
$row->[15] = '';
if ($row->[5] =~ /#[^ ]+/) {
   ($row->[15]) = $row->[5] =~ /(#[^ ]+)/;
   }