It's like all these cases I read about people accidentally sending 1 BTC or 10 to the wrong address, accidentally paying 1 BTC fees, or all these accidents.

I have not once made a mistake in over 3 years of transacting, and I don't mean to say that I never will, we all are human after all, but if I'm careful sending a few dollars for a tip, I'd be damned sure I know what I'm doing if I'm playing around with 4 BTC!

Anyway, if the other side of the channel closed it, they got it, right? They can send it back nicely I'm sure=p