Adding item to cart triggers "Argument #1 must be of type Drupal\commerce_order\Entity\OrderItemInterface, null given" error in commerce_avatax

Problem/Motivation

When a product is added to the cart (i.e., a brand-new order is created in "draft" state), there are no billing or shipping profiles
available on the order. Drupal Commerce’s Order::collectProfiles() method thus returns an empty array. The AvaTax module attempts to resolve a shipping/billing profile, but encounters a null (empty) profile and subsequently triggers an error:

TypeError: Drupal\commerce_tax\Event\CustomerProfileEvent::__construct(): Argument #1 ($order_item) must be of type Drupal\commerce_order\Entity\OrderItemInterface, null given, called in /var/www/html/docroot/modules/contrib/commerce_avatax/src/AvataxLib.php on line 509 in Drupal\commerce_tax\Event\CustomerProfileEvent->__construct() (line 38 of /var/www/html/docroot/modules/contrib/commerce/modules/tax/src/Event/CustomerProfileEvent.php).

This issue arises specifically during the add-to-cart action, prior to any checkout steps that collect billing or shipping addresses.

Steps to reproduce

1 Install and enable Drupal Commerce 2.x and commerce_avatax.
2 Configure AvaTax settings.
3 Add a product to the cart (or create a new order with no shipping/billing information).
4 Observe the error, as no profiles exist on the brand-new draft order at that stage.

Proposed resolution

• Update AvaTax’s AvataxLib::prepareTransactionsCreate() logic to gracefully handle cases where a shipping or billing profile is not yet present on the order item. This prevents a null reference from being passed to CustomerProfileEvent.
• Alternatively, add checks in resolveCustomerProfile() to ensure that an empty profile is skipped if it doesn’t exist.

Remaining tasks:

• [ ] Discuss how AvaTax expects to handle orders at an early "add to cart" stage.
• [ ] Decide whether focus should be on gracefully handling missing profiles or preventing AvaTax from being applied to incomplete draft orders.
• [ ] Provide patch or merge request in the commerce_avatax repository.
• [ ] Write tests confirming that the order can still be placed into the cart with no fail when no billing/shipping profile is present.

API changes:

None anticipated. The solution only adds safety checks around order item profiles.

Data model changes:

None anticipated.

Additional information:

• This behavior is consistent with Drupal Commerce 2.x, as new orders initially have no stored address profile.
• The error occurs only when the AvaTax integration tries to calculate tax for a brand-new order with no addresses.

This is actually fixed in the DEV version in this commit:

https://git.drupalcode.org/project/commerce_avatax/-/commit/d79662a0685b...

    try {
      // Allow the customer profile to be altered, per order item.
      $event = new CustomerProfileEvent($customer_profile, $order_item);
    }
    catch (\Throwable $t) {
      // The order of parameters changed in Commerce 3, this is our way of
      // supporting both versions.
      $event = new CustomerProfileEvent($order_item, $customer_profile);
    }

Now knowing this, I think we should either set commerce:^2.0 as requirement on the stable version of commerce_avatax. Or up the stable version to include the support of both commerce core version in the stable branch of commerce_avatax.

Without it one cannot add items to the cart with commerce_avatax stable + commerce_core 2.0

Instead of try/catch, named parameters would be a better IMO. With the order of Commerce 3.x

$event = new CustomerProfileEvent(order_item: $order_item, customer_profile: $customer_profile);

PHP 8 is required for this, which is already declared in composer.json.

3.x constructor of Drupal\commerce_tax\Event\CustomerProfileEvent.php

/**
  * Constructs a new CustomerProfileEvent.
  *
  * @param \Drupal\commerce_order\Entity\OrderItemInterface $order_item
  *   The order item.
  * @param \Drupal\profile\Entity\ProfileInterface|null $customer_profile
  *   The initially selected customer profile, NULL if not yet known.
  */
public function __construct(OrderItemInterface $order_item, ?ProfileInterface $customer_profile = NULL) {
  $this->orderItem = $order_item;
  $this->customerProfile = $customer_profile;
}

2.4 constructor of Drupal\commerce_tax\Event\CustomerProfileEvent.php

/**
   * Constructs a new CustomerProfileEvent.
   *
   * @param \Drupal\profile\Entity\ProfileInterface $customer_profile
   *   The initially selected customer profile.
   * @param \Drupal\commerce_order\Entity\OrderItemInterface $order_item
   *   The order item.
   */
  public function __construct(ProfileInterface $customer_profile = NULL, OrderItemInterface $order_item) {
    $this->customerProfile = $customer_profile;
    $this->orderItem = $order_item;
  }