Fit.Core.Clone(..) replaces undefined in arrays with null

[Jemt]

Arrays containing undefined will have this "value" replaced by null as the following example demonstrates:

Fit.Core.Clone({ List: ["a", undefined, "c"] }); outputs { List: ["a", null, "c"] }

The problem is related to the Clone function's internal use of JSON.stringify(..) which behaves exactly like that: JSON.stringify(["a", undefined, "b"]) outputs ["a", null, "c"]