You have created a new block and will be adding this block on every page. The block contains user-specific information and cannot be cached. The block is added to the default.xml with:

What does this accomplish?

You need to find all orders in the processing state. You have written the code:

How do you resolve the exception?

A third-party module uses a layout update that changes the template path for a core block from product/view/addto/compare.phtml of the Magento_Catalog module to custom/view/addto/compare.phtml of your custom module. The merchant has a customized version of this template in their custom theme.
What is a consequence of this setup?

You are debugging a problem resulting from a recently deployed around plugin. The plugin is intercepting the doSomething method. The aroundDoSomething plugin method is called successfully, but the original doSomething method is no longer being executed as expected.
What is causing this?

You are reviewing a Magento module and see a directory named Service.
What can you determine from this directory's name?