this is happening on hhvm, so either test.wikidata or perhaps wikivoyage, wikisource, commons etc.
Fatal error: Argument 1 passed to Wikibase\InternalSerialization\Deserializers\LegacyClaimDeserializer::setRank() must be an instance of Wikibase\DataModel\Claim\Statement, Wikibase\DataModel\Statement\Statement given in /srv/mediawiki/php-1.25wmf1/extensions/Wikidata/vendor/wikibase/internal-serialization/src/Deserializers/LegacyClaimDeserializer.php on line 106
Version: unspecified
Severity: normal