test: remove unreachable code

There is no way a line can be called after throwing an exception.

PR-URL: https://github.com/nodejs/node/pull/2289


Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Brendan Ashworth <brendan.ashworth@me.com>