Javascript errors on private-message/create page

Not exactly sure why, but apparently inside the .each() functions $(this) was undefined. so instead I changed it to use the element parameter in the each function. This MR seems to resolve the issue for me.

Apparently due to 📌 Allow for deletion of a single value of a multiple value field Fixed adding a remove button to multi value reference fields, this module's js was triggering the 'remove' button instead of the 'add more' button of the hidden member reference field, resulting in js errors when attempting to add members to a thread.

My MR attempts to clear this up.

I am not able to replicate the issue.
* I pulled the latest 3.0.x version,
* visited /private-message/create
* used autocompletion
* I didn't notice any errors

Can you verify the issue on the latest version?

Issue with $config initialization is covered by https://www.drupal.org/project/private_message/issues/3485607 🐛 Error when entering comma-separated usernames Active , thanks for help!

Postponed to get more feedback from @loze