VBA, HandleToObject and handles of deleted entities.

I'm doing some tests with VBA and I'm having a problem:

    Public Sub Test()
        Dim p1 As Point
        Set p1 = Library.CreatePoint(0, 0, 0)
        Dim p2 As Point
        Set p2 = Library.CreatePoint(50, 50, 0)
        Dim l As Line
        Set l = ThisDocument.ModelSpace.AddLine(p1, p2)

        Dim h As String
        h = l.Handle

        l.Delete

        Dim o As Object
        Set o = ThisDocument.HandleToObject(h)
    End Sub

On the last line of the Sub,

    Set o = ThisDocument.HandleToObject(h)

h is the handle of a deleted line, but HandleToObject returns the line
without a problem. In Autocad a similar situation would raise an
exeption. Is it possible to know when, given a handle, the respective
entity exists or not?

Thanks