aldeed/meteor-simple-schema — pull request #34 by wsoul (2013-11-15 17:57:57+00:00)
Title: isModified, empty object check [bugfix]

Throw exceptions in next situation:

CollectionName.update(someId, { $set: { nonexistentKey: anyValue } });

Otherwise object will be updated to { "_id": "someId" }
In other words, object will be rewritten by empty object.