Invoice addComment can throw error when Invoice getComments is called first

[mihaimatei]

Preconditions and environment

The Invoice model module-sales/Model/Order/Invoice.php can return both a collection or an array. If the invoice object has the 'comments' data key, it will just return it, regardless of it being sometimes an array, like when $invoice->getComments() was called before attempting to add a comment. One reason for this would be that both getComments() and getCommentsCollection() are using the same InvoiceInterface::COMMENTS data key to get/set data, but using different data types (array vs collection) to populate it.
Example to replicate:

$invoice = $this->invoiceRepository->get($invoiceId);
$commentsCollection = $invoice->getComments();
$invoice->addComment('whatever', false, false);

So a call to $invoice->addComment() is causing Error: Call to a member function addItem() on array in /var/www/html/vendor/magento/module-sales/Model/Order/Invoice.php:716.
Comparing getCommentsCollection() method between Invoice and CreditMemo models, reveals the different implementation.

For the above example, adding $invoice->unsetData(InvoiceInterface::COMMENTS); right before the addComment call, will make it work, because due to not having the comments key will make getCommentsCollection() return a proper collection.

Affected versions: 2.4.7, 2.4.8 (I've only checked and confirmed the code issue on these versions)

Steps to reproduce

Implement the following sequence in a custom module:

$invoice = $this->invoiceRepository->get($invoiceId);

$commentsCollection = $invoice->getComments();    
// will set the invoice object data key InvoiceInterface::COMMENTS with an array value

$invoice->addComment('whatever', false, false);
// will further call getCommentsCollection() which will return the array from data key InvoiceInterface::COMMENTS
//   on which ->addItem() will be called, causing the error

Expected result

Comment is added to the invoice

Actual result

Error: Call to a member function addItem() on array in /var/www/html/vendor/magento/module-sales/Model/Order/Invoice.php:716

Additional information

No response

Release note

No response

Triage and priority

• Severity: S0 - Affects critical data or functionality and leaves users without workaround.
• Severity: S1 - Affects critical data or functionality and forces users to employ a workaround.
• Severity: S2 - Affects non-critical data or functionality and forces users to employ a workaround.
• Severity: S3 - Affects non-critical data or functionality and does not force users to employ a workaround.
• Severity: S4 - Affects aesthetics, professional look and feel, “quality” or “usability”.

[m2-assistant]

Hi @mihaimatei. Thank you for your report.
To speed up processing of this issue, make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce.

• For more details, review the Magento Contributor Assistant documentation.
• Add a comment to assign the issue: @magento I am working on this
• To learn more about issue processing workflow, refer to the Code Contributions.

---

Join Magento Community Engineering Slack and ask your questions in #github channel.
⚠️ According to the Magento Contribution requirements, all issues must go through the Community Contributions Triage process. Community Contributions Triage is a public meeting.
🕙 You can find the schedule on the Magento Community Calendar page.
📞 The triage of issues happens in the queue order. If you want to speed up the delivery of your contribution, join the Community Contributions Triage session to discuss the appropriate ticket.

[m2-assistant]

Hi @engcom-November. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

• 1. Verify that issue has all the required information. (Preconditions, Steps to reproduce, Expected result, Actual result).
• 2. Verify that issue has a meaningful description and provides enough information to reproduce the issue.
• 3. Add Area: XXXXX label to the ticket, indicating the functional areas it may be related to.
• 4. Verify that the issue is reproducible on 2.4-develop branch
  Details

  - If the issue is reproducible on 2.4-develop branch, please, add the label Reproduced on 2.4.x.
  - If the issue is not reproducible, add your comment that issue is not reproducible and close the issue and stop verification process here!
• 5. Add label Issue: Confirmed once verification is complete.
• 6. Make sure that automatic system confirms that report has been added to the backlog.

[m2-assistant]

Hi @engcom-Hotel. Thank you for working on this issue.
In order to make sure that issue has enough information and ready for development, please read and check the following instruction: 👇

• 1. Verify that issue has all the required information. (Preconditions, Steps to reproduce, Expected result, Actual result).
• 2. Verify that issue has a meaningful description and provides enough information to reproduce the issue.
• 3. Add Area: XXXXX label to the ticket, indicating the functional areas it may be related to.
• 4. Verify that the issue is reproducible on 2.4-develop branch
  Details

  - If the issue is reproducible on 2.4-develop branch, please, add the label Reproduced on 2.4.x.
  - If the issue is not reproducible, add your comment that issue is not reproducible and close the issue and stop verification process here!
• 5. Add label Issue: Confirmed once verification is complete.
• 6. Make sure that automatic system confirms that report has been added to the backlog.

[engcom-Hotel]

Hello @mihaimatei,

Thanks for the report and collaboration!

We have tried to reproduce the issue in the latest 2.4-develop branch and it seems the issue has been reproducible for us. We are getting the same error as you mentioned in the description:

Call to a member function addItem() on array#0 generated/code/Magento/Sales/Model/Order/Invoice/Interceptor.php(266): Magento\Sales\Model\Order\Invoice->addComment(Object(Magento\Sales\Model\Order\Invoice\Comment), false, false)

Hence confirming the issue.

Thanks