Guard MSI UpgradeCode lookup against missing registry key

[Tom Plant (pl4nty)]

Get-ADTApplication built its MSI UpgradeCode lookup table with an unguarded Get-ChildItem on
HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes. On machines where that key does not exist (e.g. images with no MSI-registered upgrade codes), Get-ChildItem threw a PathNotFound error that aborted the function's begin block, breaking any caller such as Uninstall-ADTApplication.

Add -ErrorAction Ignore to match the pattern already used for the uninstall key enumeration. When the key is absent the pipeline yields no items, the scriptblock's begin/end blocks still run, and the lookup table is simply empty; downstream indexing already returns $null for GUIDs that are not present.

Claude-Session: https://claude.ai/code/session_01XLNM98Nd3HZLTWFatRVgB1

Pull Request

Description

Please include a summary of any changes. Please also include relevant motivation and context.

Fixes: #12345

Fixes: https://github.com/PSAppDeployToolkit/PSAppDeployToolkit/issues/12345

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• General code cleanup (non-breaking change which improves readability)

Checklist

• I am pulling to the main branch
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have tested my changes to prove my fix is effective
• I have tested that the module can build following my changes
• I have made sure that any script file-encoding is set to UTF8 with BOM, i.e. unchanged.

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration.