Component instantiation with viewModel prop to null dosent work

[cherifGsoul]

I have this component:

var ComponentCtor = Component.extend({
   tag: 'a-tag',
   ViewModel: {
       foo: {
         default() {
            return "bar";
         }
      }
    }
});

when the component is instantiated like this:

var componentInst = new ComponentCtor({
   viewModel: {
        foo: null
    }
});

It throws an error Uncaught TypeError: Cannot read property 'Symbol(can.getValue)' of null