The XML dumps of Wikidata contain many JSON serialization errors where empty maps {} are wrongly serialized as empty lists []. This affects many different fields, such as "claims", "aliases", and "descriptions", and it seems likely that all empty maps are serialized wrongly.

This is a major inconvenience to all users who for some reason or other prefer XML over the JSON dumps (which do not have the problem). In particular, the XML dumps are needed to get access to the full history of the pages. Using the same JSON as used in the JSON dumps would fix the problem.