Optional properties sometimes complain about `NSNull` (`desired type = NSString; given type = NSNull`)

[helje5]

I'm sometimes getting this:

Unacceptable type of value for attribute: property = "xyz"; desired type = NSString; given type = NSNull; value = .

In this:

  func setValue<T>(forKey key: String, to value: T)
    where T: Codable & CoreDataPrimitiveValue & AnyOptional
  {
    willChangeValue(forKey: key); defer { didChangeValue(forKey: key) }
    let attr = Self.entity().attributesByName[key]
    print("Attr:", attr?.name, attr?.isOptional, attr?.attributeValueClassName)
    setPrimitiveValue(value, forKey: key)
  }

The property is optional, the valueClassName is set to NSString. Not quite sure what is going on here.

In CoreData those work:

    let item = Item(entity: Item.entity(), insertInto: nil)
    assert(item.entity === entity)
    
    item.value = nil
    item.setPrimitiveValue(nil, forKey: "value")

but this fails as well:

    item.setPrimitiveValue(NSNull(), forKey: "value")

Maybe a bridging issue w/ nil? As far as I can see, nil is properly used.

It fails in coerceValueForKey.

[helje5]

Fixed.