The only way this (my) code can throw a division by zero error is when you tell the program to read an empty data file. This can be mitigated.

sub average_hourly_wage{
    my $self = shift;
    my $wages = 0; my $count = 0;
    
    foreach my $employee ( @{ $self->{EmployeeList} })
    {
        $wages += $employee->{hourlywage}; $count++;
    }
    
    return $count ? $wages / $count : 0;
}
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And of course, if the data file is empty, there is nothing in the Employee-List, thus ->find returns undef. That however, is something you have to deal with in the calling code.

if ( my $e = $EmployeeList->find("holli") )
{
    print $e->pay, "\n";
} 
else
{
    print "User not found\n";
}
[download]