fix(InternalStore): invalid value on parse

if you get an invalid value JSON.parse throws an error

localcache = {
  'yolo': undefined // should be "{swag: true, isAuthenticated: true}"
};

store.get('yolo') // JSON.parse error is thrown


localcache
Just one more little change, just set the `obj` to `null` when instantiating it so that you don't have to set it in the catch.

That way one less line and we still return after the try catch. Thanks!