I am pulling data out of a .csv file and doing a calculation, then putting the data into an excel file. I tried the following:

if(@$data[$i]->{"Date1"} eq "" || @$data[$i]->{"Date2"} eq ""){
### getting error from above line
    $days = "N/A";
}
else{
    my $t1 = Time::Piece->strptime(@$data[$i]->{"Date1"},"%m/%d/%Y");
    my $t2 = Time::Piece->strptime(@$data[$i]->{"Date2"},"%m/%d/%Y");
    $days = $t2 - $t1;
    $days = int($days->days);
    }
$ws->write(1, $i+1, $i+1, $colhdr);
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I am getting an error saying that it is an un-initialized variable in the string where marked. The program still runs and gives me the file I want, but I just want to understand and get rid of the error. Thanks for the input
FYI, I am debugging in Komodo IDE

Thanks everyone for input. I found the error. It was in my .csv file. There were a few blank lines so they didn't get the comma separation. After deleting the lines, the error went away and the program works. Thanks again though :)