Replace null-coalescing operators with PS5.1-compatible syntax

[Copilot]

Plaster v2.0.0-alpha uses the null-coalescing operator (??) introduced in PowerShell 7.0, breaking compatibility with PowerShell 5.1 as specified in the module manifest.

Changes

Write-PlasterLog.ps1

• Replaced ?? operators with conditional expressions compatible with PS5.1+

# Before
$currentLogLevel = $script:LogLevel ?? 'Information'
$currentLevelValue = $logLevels[$currentLogLevel] ?? 2

# After
$currentLogLevel = if ($null -ne $script:LogLevel) { $script:LogLevel } else { 'Information' }
$currentLevelValue = if ($null -ne $logLevels[$currentLogLevel]) { $logLevels[$currentLogLevel] } else { 2 }

Plaster.psm1

• Added dot-sourcing for Private and Public function files
• Implemented selective export of public functions only

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• www.powershellgallery.com
  • Triggering command: /usr/bin/pwsh pwsh -NoProfile -File ./build.ps1 -Bootstrap (dns block)
  • Triggering command: /usr/bin/pwsh pwsh -NoProfile -Command Register-PSRepository -Default -ErrorAction SilentlyContinue Get-PSRepository (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Plaster v2.0.0-alpha broken on Windows</issue_title>
<issue_description>Hiya,

Sampler uses Plaster and we've noticed on our pipelines that the prerelease version breaks on windows because Write-PlasterLog uses the Null-coalescing operator.

https://github.com/PowerShellOrg/Plaster/blob/v2/Plaster/Private/Write-PlasterLog.ps1#L52-L54

Could you please fix soonish, or would you recommend we pin an old version?</issue_description>

<agent_instructions>Search for any use of null coalescing and remove it. This module must be able to run PS5.1</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Plaster v2.0.0-alpha broken on Windows #442

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[github-actions]

Test Results

  3 files  189 suites   35s ⏱️
210 tests 208 ✅ 2 💤 0 ❌
630 runs  624 ✅ 6 💤 0 ❌

Results for commit e019b41.

♻️ This comment has been updated with latest results.

[HeyItsGilbert]

LGTM