snapshots method
Returns a stream that emits a DocumentReference with the latest data from the server or null if the document is deleted or does not exist on the server.
Implementation
Observable<DocumentData?> snapshots() => _queryBuilderFactory
.getForDocument(squidDocId)
.dereference()
.snapshots()
.map((results) {
assert(results.length <= 1,
'Got more than one doc for the same id: $squidDocId');
return results.firstOrNull;
});