Use of uninitialized value in array element at (eval 9) line 4.

##</code><code>##

#!/usr/bin/perl

use warnings;

my $code_err = q|
my @arr;
my $i;
$arr[$i] = 0;     # line 4 within this code snippet
|;

my $code_ok = q|my $var = ""|;

eval $code_ok for (1..8);
eval $code_err;   # 9th eval, but line 14 in this script