CoreTransformer crashes if stmt is empty

[SergioAlonsoJr]

Not sure if it's intentional, but this test will crash if added to CoreTransformerTest.scala

test("Check empty stmt Transformation") {
    val module = ScalaParser.parseResource("simple/simple01.oberon")
    new CoreVisitor().transformModule(module)
}

Contents of simple01.oberon:

MODULE SimpleModule1;

CONST
  x = 5;

END SimpleModule1.