ahawkins/chassis — pull request #8 by terlar (2014-06-04 22:30:59+00:00)
Title: Fix ParameterMissingError message

It referred to an instance variable instead of the block variable causing this
error to return a very confusing message.

I have looked through the tests and see there are no specific tests for the
error messages. Should it be added?

Perhaps just something that checks that the key is contained within the error
message.