Simulate undefined properties update error

[LorenzoSantoro94]

By default, Firestore throws error when calling update with an object containing undefined values.
Behavior is described here https://firebase.google.com/docs/reference/js/v8/firebase.firestore.Settings#optional-ignoreundefinedproperties
It would be nice simulating the same exception (or not if disabled) with this library.

Basic example

db.collection('myCollection').doc(id).update({
prop: undefined
})