Creation of zero symbol has non-null import location

[byronlin13]

var reader = new UserTextReader("$0::18");
reader.MoveNext();
Assert.IsTrue(reader.GetTypeAnnotationSymbols().Any(a => a.ImportLocation == null));

The following code fails, upon debugging, a.ImportLocation returns:

{ImportLocation::{importName:, id:0}}

Expected scenario: annotation contains null import location