Setting a property on a model that hasn't been downloaded yet deletes all existing properties of that model

[vladpke]

In the code snippet below, when executing the line employee.warehouseID = warehouseID; before the data of the Warehouse model was downloaded, all other properties of that model on Firebase are deleted.
let warehouseID = 'someID';
const employee = Injection.get(Employee, uid);
employee.warehouseID = warehouseID;