What is the issue with checking for the existence of $newItem in the $_SESSION['items'] array?

The issue with checking for the existence of $newItem in the $_SESSION['items'] array is that the code may throw an error if $_SESSION['items'] is not set or is not an array. To solve this, you can first check if $_SESSION['items'] is set and is an array before checking for the existence of $newItem in it. 

<?php
session_start();

// Check if $_SESSION['items'] is set and is an array
if(isset($_SESSION['items']) && is_array($_SESSION['items'])) {
    $newItem = 'item1';

    // Check if $newItem exists in $_SESSION['items']
    if(in_array($newItem, $_SESSION['items'])) {
        echo 'Item already exists in the session.';
    } else {
        $_SESSION['items'][] = $newItem;
        echo 'Item added to session.';
    }
} else {
    echo 'Session items not found or not an array.';
}
?>

Keywords

PHP $_SESSION array isset key_exists

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