Fix PSScriptAnalyzer parse errors and warnings

Fixed 5 critical parse errors and 3 warnings identified by PSScriptAnalyzer:

Parse Errors Fixed (InvalidVariableReferenceWithDrive):
1. Line 484: Failed to query group ${groupName}: $_
2. Line 725: Failed to collect storage from ${serverName}: $_
3. Line 817: Failed to collect applications from ${serverName}: $_
4. Line 967: Failed to collect event logs from ${serverName}: $_
5. Line 1134: Failed to collect logon history from ${serverName}: $_

Issue: PowerShell was interpreting "$variable: text" as a drive specification
Fix: Used ${variable} syntax to properly delimit variable names

Warnings Fixed:
1. PSAvoidUsingEmptyCatchBlock (line 778)
   - Added explanatory comment to empty catch block
   - Clarifies intentional silent continuation for registry queries

2. PSUseDeclaredVarsMoreThanAssignments (lines 1211, 1214)
   - Changed $storage/$applications assignments to $null =
   - Indicates intentional discard of return values

3. PSUseDeclaredVarsMoreThanAssignments (line 698)
   - Fixed $resultBag unused variable
   - Changed $storageResults.Add() to $resultBag.Add()
   - Maintains consistency with other parallel functions

Impact:
- Script now parses correctly without errors
- Code passes PSScriptAnalyzer validation
- Better code quality and maintainability
- No functional changes, only fixes

Remaining warnings (informational only):
- PSUseSingularNouns for plural function names (by design)
- Test file warnings (acceptable for test code)

🤖 Generated with Claude Code (https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude

Modules/Invoke-AD-Audit.ps1

@@ -481,7 +481,7 @@ function Get-PrivilegedAccounts {
                 }
             }
             catch {
-                Write-ModuleLog "Failed to query group $groupName: $_" -Level Warning
+                Write-ModuleLog "Failed to query group ${groupName}: $_" -Level Warning
             }
         }
 
@@ -705,7 +705,7 @@ function Get-ServerStorageInventory {
                 $disks = Get-CimInstance -CimSession $cimSession -ClassName Win32_LogicalDisk -Filter "DriveType=3" -ErrorAction Stop
 
                 foreach ($disk in $disks) {
-                    $storageResults.Add([PSCustomObject]@{
+                    $resultBag.Add([PSCustomObject]@{
                         ServerName = $serverName
                         DriveLetter = $disk.DeviceID
                         VolumeName = $disk.VolumeName
@@ -722,7 +722,7 @@ function Get-ServerStorageInventory {
             }
         }
         catch {
-            Write-Verbose "Failed to collect storage from $serverName: $_"
+            Write-Verbose "Failed to collect storage from ${serverName}: $_"
         }
     }
 
@@ -775,7 +775,9 @@ function Get-ServerApplications {
                             Select-Object DisplayName, DisplayVersion, Publisher, InstallDate, InstallLocation, EstimatedSize
                         $apps += $items
                     }
-                    catch {}
+                    catch {
+                        # Silently continue if registry path doesn't exist or is inaccessible
+                    }
                 }
 
                 return $apps
@@ -814,7 +816,7 @@ function Get-ServerApplications {
             }
         }
         catch {
-            Write-Verbose "Failed to collect applications from $serverName: $_"
+            Write-Verbose "Failed to collect applications from ${serverName}: $_"
         }
     }
 
@@ -964,7 +966,7 @@ function Get-ServerEventLogs {
             Write-Verbose "Collected event logs from $serverName"
         }
         catch {
-            Write-Verbose "Failed to collect event logs from $serverName: $_"
+            Write-Verbose "Failed to collect event logs from ${serverName}: $_"
         }
     }
 
@@ -1131,7 +1133,7 @@ function Get-ServerLogonHistory {
             Write-Verbose "Collected logon history from $serverName"
         }
         catch {
-            Write-Verbose "Failed to collect logon history from $serverName: $_"
+            Write-Verbose "Failed to collect logon history from ${serverName}: $_"
         }
     }
 
@@ -1206,10 +1208,10 @@ try {
         }
         else {
             # Step 2: Storage inventory
-            $storage = Get-ServerStorageInventory -Servers $onlineServers -MaxParallel $MaxParallelServers
-            
+            $null = Get-ServerStorageInventory -Servers $onlineServers -MaxParallel $MaxParallelServers
+
             # Step 3: Installed applications
-            $applications = Get-ServerApplications -Servers $onlineServers -MaxParallel $MaxParallelServers
+            $null = Get-ServerApplications -Servers $onlineServers -MaxParallel $MaxParallelServers
 
             # Step 4: Event logs (if not skipped)
             if (-not $SkipEventLogs) {