Pash-Project/Pash — pull request #183 by sburnicki (2013-12-04 20:28:59+00:00)
Title: Undefined variables evaluate to null

Undefined variables always caused a NullReferenceException.
However, this is not the standard behavior of powershell, which can lead
to problems. Therefore, as in powershell, undefined variables will
evaluate to null if they are used in a normal expression.