Fix null-handling errors in DHCP report generation

[BitWise-0x]

Summary

A DHCP report run against an environment with ~10 servers produced 700+ terminating errors in the verbose log while still completing. They trace to three null-handling defects.

Details

1. ConvertTo-TextYN / ConvertTo-EmptyToFiller throw on $null

Both declare [string] $TEXT with [AllowEmptyString()] but not [AllowNull()]. A $null argument is rejected by the parameter binder before the body runs:

TerminatingError(ConvertTo-TextYN): "Cannot process argument transformation on parameter 'TEXT'. Cannot convert value to type System.String."

The existing $Null { "--" } switch case is unreachable as a result. DHCP properties that legitimately return null (e.g. failover AutoStateTransition / EnableAuth, option-definition MultiValued) hit this and leave blank cells in the report. The failover ones surface in the log as (IPv4 Scope Failover Item) warnings. Adding [AllowNull()] lets null reach the body and render as --.

2. ConvertTo-HashToYN iterates the wrong variable

The loop enumerates $inObj, which is never defined in the function; it should enumerate the $TEXT parameter. As written the conversion loop does nothing.

3. Get-AbrADDHCPDomain calls Get-ADDomain before validating the domain

foreach ($Domain in ($OrderedDomains.split(" "))) can yield an empty element, and Get-ADDomain is called before the if ($Domain) guard:

TerminatingError(Get-ADDomain): "Cannot validate argument on parameter 'Identity'. The Identity property on the argument is null or empty." (DHCP Servers Section)

Guarding $Domain in the outer if (and testing $DomainInfo afterwards) skips the empty entry.

Changes

• SharedUtilsFunctions.ps1 - add [AllowNull()] to ConvertTo-TextYN and ConvertTo-EmptyToFiller; fix ConvertTo-HashToYN to enumerate $TEXT
• Get-AbrADDHCPDomain.ps1 - validate the domain value before Get-ADDomain, test $DomainInfo for the section guard
• CHANGELOG.md - Unreleased / Fixed entries

Testing

ConvertTo-TextYN exercised against $null, '', ' ', 'True', 'False', and arbitrary text - null/empty/space now return --, booleans return Yes/No, and no terminating error is raised. Both changed files parse cleanly.

[rebelinux]

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