They did change something with regards to those get operations. In some cases they now throw an exception instead of returning null.
But in this case, I think it's more like an internal change in the way the API gets objects. If an object doesn't have a packageID, it should not exist.
The GUI will not show you this object, and the Project Integrity Check will rescue these orphans and give them a new home (package).
So I'm afraid your "elements without a package) workaround is simply a wrong approach that needs refactoring.
(also, what happens if someone creates a second object with he name "ColoresAddinGobiernoDinamico"?)
Geert
PS. There is a faster way to get elements based on a query. You can use Repository.GetElementSet(query, 2). That saves you the trouble of parsing the XML, getting the ID, and a roundtrip to the database to get the object.