Compile-Time Error

<?php
$startDate = $_GET['dateOne'];
$endDate = $_GET['dateTwo'];
$holidaysText = preg_split('/\s+/', $_GET['holidays'], -1, PREG_SPLIT_NO_EMPTY);
$holidays = [];
$workDays = [];
$start = new DateTime($startDate);
$end = new DateTime($endDate);
if($start > $end){
    echo "<h2>No workdays</h2>";
    die;
}
for($i = 0; $i < count($holidaysText); $i++){
    $holidays[$i] = new DateTime($holidaysText[$i]);
}

$counter = 0;
while($start <= $end){
    $currentDate = clone $start;
    if(!in_array($currentDate, $holidays) &&
       date( "w", $currentDate->getTimestamp()) != 6 &&
       date( "w", $currentDate->getTimestamp()) != 0) {
        $workDays[$counter] = $currentDate;
        $counter++;
    }
    $start->modify("+1day");
}
echo "<ol>";
foreach ($workDays as $workDay) {
    $a = $workDay->format("d-m-Y");
    echo "<li>$a</li>";
}
echo "</ol>";