Guard MSI UpgradeCode lookup against missing registry key

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.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XLNM98Nd3HZLTWFatRVgB1

Author: claude

src/PSAppDeployToolkit/Public/Get-ADTApplication.ps1

@@ -178,7 +178,7 @@ function Get-ADTApplication
 
         # Define compiled regex for use throughout main loop.
         $updatesAndHotFixesRegex = [System.Text.RegularExpressions.Regex]::new('((?i)kb\d+|(Cumulative|Security) Update|Hotfix)', [System.Text.RegularExpressions.RegexOptions]::IgnoreCase -bor [System.Text.RegularExpressions.RegexOptions]::Compiled)
-        $msiUpgradeCodeLookupTable = Get-ChildItem -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes\* | Get-ItemProperty | & {
+        $msiUpgradeCodeLookupTable = Get-ChildItem -Path HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UpgradeCodes\* -ErrorAction Ignore | Get-ItemProperty | & {
             begin
             {
                 # Open lookup table dictionary for returning at the end.