Logstash-input-rss error with tag<image>

I am using logstash 2.3.4 with the rss plugin to attempt to
ingest this rss feed https://www.technologyreview.com/stories.rss.
My conf file is defined as the following which I tested with the --configtest option.
input {
rss {
interval => 600
url => "https://www.technologyreview.com/stories.rss"
output {

I get the following error message when I start logstash:
A plugin had an unrecoverable error. Will restart this plugin.
Plugin: <LogStash::Inputs::Rss interval=>600, url=>"https://www.technologyreview.com/stories.rss", codec=><LogStash::Codecs::Plain charset=>"UTF-8">>Error: tag is missing in tag {:level=>:error}

Based on the error it looks like a tag is just missing. Is there a way I can figure my
config file to recognize the tag, or is this something that requires a fix in the rss plugin?