Seems that the ruby-tumblr Ruby gem doesn’t support Audio posts - and when it encounters them, it bombs with a NilClass exception rather than failing gracefully.
I’m going to get a patch to the ruby-tumblr Google group (as requested by the author) in the next few days, and if that gets no response - I’m worried that the project might be dead, with its last release in 2007 - I’ll fork it on Github.
In the meantime, if you need a quick fix, the problem is located in the ‘case’ block near line 70 in tumblr.rb - on Mac OS X, this is stored in “/Library/Ruby/Gems/1.8/gems/ruby-tumblr-0.0.2/lib/tumblr.rb”.
