Reference to wrong / non-existing class

[tzyganu]

Preconditions

1. Magento version 2.2 (or previous)

Steps to reproduce

1. In the method Magento\Sales\Model\Order\Pdf\Invoice::getPdf comment out the call to $this->insertOrder(
2. Go to the backend and print an invoice

Expected result

1. I should see the invoice without the order details

Actual result

1. I get a fatal error because the class Zend_Pdf_Color_RGB is not found in the _drawHeader method.

Additional info

This happens because the actual class name is Zend_Pdf_Color_Rgb (lowercase g and b).
The fact that it works is just an accident. It's because that's how the php autoloader works. The correct class name is referenced in a method called above the _drawHeader and the correct file is found. The second time the class is called the class is already loaded and since the class names are not case sensitive .... you get where this is going.

Same goes for creditmemo and shipping print. I guess copy/paste.

[magento-engcom-team]

@tzyganu, thank you for your report.
We've created internal ticket(s) MAGETWO-82432 to track progress on the issue.

[magento-team]

Internal ticket to track issue progress: MAGETWO-82428