i see numerous entries for this, though it's on the old branch. maybe it's fixed in master....
Warning: Encountered an Entity without EntityId in EntityParserOutputGenerator. [Called from Wikibase\EntityParserOutputGenerator::getParserOutput in /srv/mediawiki/php-1.26wmf15/extensions/Wikidata/extensions/Wikibase/repo/includes/EntityParserOutputGenerator.php at line 206] in /srv/mediawiki/php-1.26wmf15/includes/debug/MWDebug.php on line 300