Fatal error: Uncaught Error: Undefined constant "​" and array question – Phpmyadmin

I’m trying to make a foreach function where a number in a table in phpmyadmin will increase each time value inside an array matches the "pet_id". And also this only execute whenever a submit button is pressed. This is my code in php file:

<?php
    if (isset($_POST['Submit'])) {
        if (isset($cart)) {
            // if product appeared
            foreach ($product->getData('cart') as $item):
                $cart = $product->getProduct($item['pet_id']);
                $subTotal[] = array_map(function ($item){
                    $sql = "UPDATE pet_info SET number_sold = number_sold + 1 WHERE 
                    $item == pet_info.pet_id;";

                    $query1 = mysqli_query($con,$sql);
                    while ($pet_id = mysqli_fetch_array($query1)) {
                        execute($pet_id['pet_id']); 
                    }
                }); 
            endforeach;
        }   
    }​
?>

But I spent the last 2 hours searching for a solution but what i achieve is still errors:

Fatal error: Uncaught Error: Undefined constant "​" in C:xampphtdocstestingpetsonthenetpartial_checkout.php:121 Stack trace: #0 C:xampphtdocstestingpetsonthenetuser_cart.php(7): include() #1 {main} thrown in C:xampphtdocstestingpetsonthenetpartial_checkout.php on line 121

Can someone help me please? I’d be very appreciated!!

This is the part of the code related to the cart

                <?php
                foreach ($product->getData('cart') as $item) :
                    $cart = $product->getProduct($item['pet_id']);
                    echo gettype($item);
                    $subTotal[] = array_map(function ($item){
            ?>
            <!-- cart item -->
            <div class="row border-top py-3 mt-3">
                <div class="col-sm-2">
                    <img src="<?php echo $item['image'] ?? "./images/pet (1).jpg" ?>" style="height: 150px; width:120px;" alt="cart1" class="img-fluid">
                </div>
                
                <div class="col-sm-8">
                    <h5 class="font-baloo font-size-20"><?php echo $item['name'] ?? "Unknown"; ?></h5>
                    <h5 class="font-baloo font-size-20"><?php echo $item['pet_id'] ?? "Unknown"; ?></h5>
                    <small> <?php echo $item['breed'] ?? "Brand"; ?></small>
                        
                </div>

                <div class="col-sm-2 text">
                    <div class="font-size-20 text-danger font-baloo">
                        $<span class="product_price" data-id="<?php echo $item['pet_id'] ?? '0'; ?>"><?php echo $item['price'] ?? 0; ?></span>
                    </div>
                </div>
                <form method="post">
                            <input type="hidden" value="<?php echo $item['pet_id'] ?? 0; ?>" name="pet_id">
                            <button type="submit" name="delete-cart-submit" class="btn font-baloo text-danger px-3 border-right">Delete</button>
                </form>
            </div>
            <!-- !cart item -->
            <?php
                        return $item['price'];
                    }, $cart); // closing array_map function
                endforeach;
            ?>