Hi,
Here is what has happened to me:
I registered to my site using flarum, a first email link has been sent, due tot he delay in the email server, I clicked on "resend link", the first link finally arrived, I clicked on it and received an error 500, the second link arrive and this one worked.
I believe that when we click on "resend link" the token become invalidated right away, but the system should send another type of message for token invalidation, ie: "This link expired" or similar. with the error 500, the user thinks that something is really wrong with the site.
Thank you.