Here's some free debugging as we all really need the service back up and running properly. Cookies and cache where completely wipped before attempting the exercise, several times. The error is consistent across operating systems, devices, browsers and even machines.
At line 356 of LoginLink.action
you are passing empty constructor arguments to a JavaScript class instantiation potentially due to a server side error failing to output the relevant arguments where they should be.
The code ends up being:
var timeout = new LoginTimeout( , );