Kotlin Koans broken!

Hi,

I was doing the Kotlin Koans online course, just taking the steps in the Introduction part.
But it’s giving me trouble when I click on Run after typing a solution in the code window.
I was able to do several pages, but then it started to give an orange error message that said “please try again” (I tried again several days later but gave the same error)

Then I tried restarting the course in Chrome instead of Firefox, but that one started to give an empty response when clicking Run. Also tested in a private (incognito) window, but it gave the same response.

The whole things appear a bit buggy / unstable to me.
Can you investigate?
Would love to take the whole course.

Thanks!

The Koans website works fine for me(although I only tried out a few of them just now). Anyways, you might want to try out the offline version of Koans if the online version does not work for you.