How can the isset() function in PHP be utilized to avoid errors in navigation highlighting?

The isset() function in PHP can be utilized to avoid errors in navigation highlighting by checking if a certain variable or array key exists before using it to determine the active state of a navigation link. This helps prevent errors when the variable or key is not set, avoiding potential issues with undefined index errors.

// Check if the current page variable is set, then use it to determine the active state of the navigation link
$current_page = isset($_GET['page']) ? $_GET['page'] : '';

// Example navigation link with active state based on current page
echo '<a href="home.php" class="' . ($current_page == 'home' ? 'active' : '') . '">Home</a>';