It was the case for me a couple of weeks ago but I just tried and it seems to be fixed now.

It was a few days ago, but it seems to be working now.

Just tried it and no error for me

500 internal error comes up occasionally here too but not only when unsmiling.

My wasn't even loading yesterday

unsmiling is not allowed, woe be onto you, for your have broken the sacred covenant

I got that every time I tried the other day (I think I was unsmiling because I think I'd already smiled them but I wasn't sure if I had and forgot which colorvwas which), I submitted an issue on Github.