Well, I can reproduce the error now, the buffer it is getting is
too long for some reason. Probably a slicing error that doesn't
show up with smaller payloads.
I should have a fix today though.
BTW, interestingly, the more complex codepath for uploads does
work fine (add enctype="multipart/form-data" to your HTML form to
trigger it, you don't actually have to do an upload, that attr is
enough) so you can do that as a work around in the mean time.
I prolly just actually tested large uploads and never did large
normal submissions with the embedded server.
