NullReferenceException when exception is raised in convention

[BernieWhite]

Description of the issue

An exception is not handled correctly when a convention raises an exception.

A new NullReferenceException is raised because a reference to RuleRecord is invalid during Begin block excecution.

Error output

Object reference not set to an instance of an object.

Module in use and version:

• Module: PSRule
• Version: 1.4.0-B2105019

Captured output from $PSVersionTable:

Name                           Value
----                           -----
PSVersion                      7.1.3
PSEdition                      Core
GitCommitId                    7.1.3
OS                             Microsoft Windows 10.0.19043
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0