When attempting to utilize this module for the purpose of adding a specific class to the options in the selector within the view filter, I encountered an issue. The problem arises when the term hierarchy option is enabled, resulting in a list of options that comprise objects. These objects, in turn, contain a nested array with the option's ID.
Unfortunately, the form_options_attributes_preprocess_form_options_attributes__select__options_attributes hook does not handle this scenario.
Try to add a taxonomy filter to the view, select the dropdown option, and use the hook to add the options_attributes form element. This won't work.
To address this, I propose the addition of an extra condition to verify if an option is an object when iterating over an array of options. In such a case, we can extract the ID from the object and utilize it as a key.
Needs review
2.0
Code
I've created a PR. Btw, I'm attaching a patch with PR changes for my own projects. I hope for someone's review.