0.9.0 is breaking chai.js

[Jimexist]

It reports that statement like this is unused statement (it is, but it's fine in chai):

expect(something).to.be.empty

[Jimexist]

See http://chaijs.com/api/bdd/#method_empty

[dcousens]

See #690 (comment), with the expectation further discussion can go there too 👍

[feross]

@Jimexist Specifically, here is the comment that explains what you can do to fix the issue: #690 (comment)