When trying to debug a case on the Google's FR webmasters forum, I noticed a problem in the schema.org documentation:

The second example in https://schema.org/Offer triggers errors when tested with the Structured Data Testing Tool: http://www.google.com/webmasters/tools/richsnippets?q=uploaded:80050431808bb1e0607ce88eb20d2a05

Is this a markup error or is it a bug in the testing tool?
Should AggregateOffer be added as a type that expects an 'offers' property?

Thanks,
Zineb