Passing a literal undefined is not a supported API, the idea is you use `raises` in one of the following ways:
* Pass a constructor by reference (QUnit will assert the exception object is an instance of that constructor)
* Pass a a regular expression (QUnit will assert exception message matches the expression)
* Skip the comparison argument <small>so the message string becomes the second parameter</code> (QUnit will assert that the block throws an exception).

Passing `undefined` is not supported, also the message is incorrect as in this case QUnit does not (and should not) assert that the exception object is an Error. If you want to assert that, then you should pass `Error` as comparison argument. When the argument is omitted QUnit will assert only that there is an exception, whether that object (indirectly) inherits from Error should not be asserted.