I get this error pretty much every time I use shell-fm. Otherwise I love the program.
Same problem here.
I'd be happy to edit some of the code if I knew which file to look at or where to start debugging.
I have this problem, too. Sometimes I can even see the track I am listening to on my last.fm page, but after it is finished it disappears from the page.
This shouldn't occur anymore since chunked HTTP responses have implemented for some time now. Let me know if it's still a problem.