Should an empty search box return an error message or all results?

I'm currently working on 2 different websites: an events and a news websites. On both sites, a search interface with filter options is provided.

Initially, the search engine was build to return an error message if the user's query was empty. Since the search engine is looking for individual items in database and not specific content within the site, I'm thinking that returning all results (i.e. all news/events in my contexts) could be an interesting functionality. The user would then have the possibility to filter down his search. This is how the search works on the Financial Times.

What are your thoughts on this matter?

Thanks :)