[Suggest] Add action and filter on message

Hi.

I am currently working on a project and find this plugin pretty useful. Thank you.

One requirement is that I do not want this plugin to create a user for me when there is no user in WP.

So when WP user not found, an error message will be printed, but I would like to customize this message, or even redirect to a URL.

Therefore, may I suggest to add a filter and an action in the message so that I can customize it myself?

Thank you very much.