Previously, the WebAPI would sometimes return a empty error. This was

because we were referring to the msg attribute of the underlying

exception, instead of casting it to a text type.
Also fix some typos that were introduced in the errors module.
Unit tests have been introduced to test the behaviour of raising a

ReopenError, CloseError, and PublishingError during a review 

request reopen, close, and publish, respectively.

Ran unit tests.