An error randomly occurs when processing AvaTax queue

[rsisco]

It has been reported that sometimes, when generating an invoice in the Magento backend, the following error is logged:

PHP Fatal error: Uncaught Error: Call to a member function getId() on null in /vendor/classyllama/module-avatax/Helper/TaxClass.php:241

Stack trace:
#0 /vendor/classyllama/module-avatax/Framework/Interaction/Tax.php(616): ClassyLlama\AvaTax\Helper\TaxClass->populateCorrectTaxClasses(Array, '1')
#1 /vendor/classyllama/module-avatax/Framework/Interaction/Tax/Get.php(123): ClassyLlama\AvaTax\Framework\Interaction\Tax->getGetTaxRequestForSalesObject(Object(Magento\Sales\Model\Order\Invoice))
#2 /vendor/classyllama/module-avatax/Model/Queue/Processing.php(350): ClassyLlama\AvaTax\Framework\Interaction\Tax\Get->processSalesObject(Object(Magento\Sales\Model\Order\Invoice))
#3 /vendor/classyllama/module-avatax/Model/Queue/Processing.php(183): ClassyLlama\AvaTax\Model\Queue\Processing->processWithAvaTax(Object(ClassyLlama\AvaTax\Model\Queue), Object(Magento\Sales\Model\Order\Invoice))

Steps to reproduce

1. Place an order
2. Generate invoice for the order
3. Process the AvaTax queue

Expected result

1. The AvaTax queue is processed without error

Actual result

1. The error indicated above is logged for some/all invoices in the queue

[rsisco]

This issue has been addressed in version 1.2.5 by changing the way the product ID is retrieved.