There were a few bursts of this error today on mediawiki.org

last one is:

2014-05-05 19:04:11 mw1133 mediawikiwiki: [0616ab78] /w/api.php?action=feedcontributions&user=MarkTraceur&feedformat=atom Exception from line 346 of /usr/local/apache/common-local/php-1.24wmf3/extensions/Flow/includes/Formatter/AbstractQuery.php: Accessing non-existent parameter: page_namespace
#0 /usr/local/apache/common-local/php-1.24wmf3/includes/api/ApiFeedContributions.php(106): Flow\Formatter\FormatterRow->__get('page_namespace')
#1 /usr/local/apache/common-local/php-1.24wmf3/includes/api/ApiFeedContributions.php(98): ApiFeedContributions->feedItem(Object(Flow\Formatter\ContributionsRow))
#2 /usr/local/apache/common-local/php-1.24wmf3/includes/api/ApiMain.php(913): ApiFeedContributions->execute()
#3 /usr/local/apache/common-local/php-1.24wmf3/includes/api/ApiMain.php(363): ApiMain->executeAction()
#4 /usr/local/apache/common-local/php-1.24wmf3/includes/api/ApiMain.php(334): ApiMain->executeActionWithErrorHandling()
#5 /usr/local/apache/common-local/php-1.24wmf3/api.php(85): ApiMain->execute()

It happens if I paste the API query, or if I query for anyone who has made a Flow contribution, e.g.

http://en.wikipedia.beta.wmflabs.org/w/api.php?action=feedcontributions&user=Spage_beta&feedformat=atom

ApiFeedContributions is asking for the page_namespace and whatever Flow formatter is responding doesn't implement a getter for that, so the "// protect against typos" handler in the parent formatter class throws this exception.

Special:Contributions doesn't call the API unless it gets an unexpected parameter, so most likely some bot or external query is calling this and failing. The api.log is so enormous I can't find the query in it.

Version: master
Severity: major