POSTing Blank XML File Raises

Using Rails 2.3.2:

$ rails test $ cd test $ script/generate controller posts create $ nano config/routes.rb # add posts resources $ nano app/controllers/posts_controller.rb # add respond_to with format.xml $ script/console

With curl:
$ touch post.xml $ curl -H 'Accept: application/xml' -H 'Content-Type: application/xml' -F upload=@post.xml http://localhost:3000/posts

This returns the default 500 error page.

The log says:

Status: 500 Internal Server Error You have a nil object when you didn't expect it! The error occurred while evaluating nil.name

/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.2/lib/active_support/xml_mini/rexml.rb:29:in `merge_element!'
/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.2/lib/active_support/xml_mini/rexml.rb:18:in `parse'
(__DELEGATION__):2:in `__send__'
(__DELEGATION__):2:in `parse'
/usr/lib/ruby/gems/1.8/gems/activesupport-2.3.2/lib/active_support/core_ext/hash/conversions.rb:154:in `from_xml'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/params_parser.rb:34:in `parse_formatted_parameters'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/params_parser.rb:11:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/rewindable_input.rb:25:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/session/cookie_store.rb:93:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/reloader.rb:9:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/failsafe.rb:11:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/lock.rb:11:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/lock.rb:11:in `synchronize'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/lock.rb:11:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/dispatcher.rb:106:in `call'
/usr/lib/ruby/gems/1.8/gems/rails-2.3.2/lib/rails/rack/static.rb:31:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/urlmap.rb:46:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/urlmap.rb:40:in `each'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/urlmap.rb:40:in `call'
/usr/lib/ruby/gems/1.8/gems/rails-2.3.2/lib/rails/rack/log_tailer.rb:17:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/content_length.rb:13:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/chunked.rb:15:in `call'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/handler/mongrel.rb:61:in `process'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `process_client'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `each'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `initialize'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `new'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `initialize'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `new'
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `run'
/usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/handler/mongrel.rb:34:in `run'
/usr/lib/ruby/gems/1.8/gems/rails-2.3.2/lib/commands/server.rb:111
/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
script/server:3