I wanted to update this after working on it this afternoon. I deactivated ALL plugins, and activated WPF *first* and it activated fine, no error.
I then re-activated ALL of the remaining plugins (via bulk) and then it threw the fatal error again, locked up the site and I had to remove WPF via ftp.
I then deactivated all plugins, activated WPF first, and then activated ALL of the other plugins *one at a time* and they all reactivated, with no fatal error with WPF still active.
That is really strange. It must have been something to do with the order they were activated in maybe? If you have any ideas, I’d like to hear them.
Unless it happens again, or unless you can replicate, I guess this isn’t really an issue.