issue:
in bsh, we can't assign and pass void type.
in javascript, we can do:
var foo = undefined // to delete foo
var foo = this.aNonExistionVar // allow
var foo = doSth(); // may return undefined

var foo = aNonExistionVar // NOT allow, special case.

bar(foo); // foo is undefined
bar(getFoo()) // allow undefined
IMHO: bsh should have those behaviors like js, because void and undefined are all useful types.
let implementers decide whether to raise an exception or not,

solvetion:
IMHO: we should remove all checking for Primitive.VOID in all classes, we just throw an exception when unwrap a void object.
we may also edit the Name.java for the special case.