Improve error reporting & handling (#741)

Scripts/Helpers/Apply-RegistryRegFile.ps1

@@ -191,6 +191,13 @@ function Invoke-RegistryOperation {
     }
 }
 
+<#
+    .SYNOPSIS
+    Applies all parsed operations from a registry file.
+
+    .OUTPUTS
+    System.Boolean. $true when all operations complete, including WhatIf; otherwise $false.
+#>
 function Invoke-RegistryOperationsFromRegFile {
     param(
         [Parameter(Mandatory)]
@@ -203,7 +210,7 @@ function Invoke-RegistryOperationsFromRegFile {
 
     if ($script:Params.ContainsKey("WhatIf")) {
         Write-Host "[WhatIf] Apply $totalOperations registry changes from '$RegFilePath'" -ForegroundColor Cyan
-        return
+        return $true
     }
 
     foreach ($operation in $operations) {
@@ -222,5 +229,8 @@ function Invoke-RegistryOperationsFromRegFile {
 
     if ($accessDeniedCount -gt 0) {
         Write-Warning "Registry fallback import completed with $accessDeniedCount access-restricted operation(s) skipped in '$RegFilePath'."
+        return $false
     }
+
+    return $true
 }

Scripts/Helpers/Import-ConfigToParams.ps1

@@ -31,6 +31,11 @@ function Import-ConfigToParams {
         throw "Failed to read config file: $resolvedConfigPath"
     }
 
+    $consistencyError = Test-ConfigConsistency -Config $configJson
+    if ($consistencyError) {
+        throw "Invalid config file '$resolvedConfigPath': $consistencyError"
+    }
+
     $importedItems = 0
 
     if ($configJson.Apps) {

Scripts/Helpers/Test-ConfigConsistency.ps1

@@ -0,0 +1,97 @@
+<#
+    .SYNOPSIS
+        Validates that a configuration file is structurally consistent before it is applied.
+
+    .DESCRIPTION
+        Returns $null when the configuration is valid, otherwise a string describing the
+        first problem found. Used by both the CLI and GUI import paths to reject invalid
+        configs before any settings are applied.
+
+    .OUTPUTS
+        System.String. $null when valid, otherwise an error message.
+#>
+function Test-ConfigConsistency {
+    param($Config)
+
+    if (-not $Config) {
+        return 'Configuration is empty or could not be read.'
+    }
+
+    if (-not $Config.Version) {
+        return 'Configuration is missing a Version field.'
+    }
+
+    if (-not $Config.Apps -and -not $Config.Tweaks -and -not $Config.Deployment) {
+        return 'The configuration file contains no importable data.'
+    }
+
+    if ($null -ne $Config.Apps) {
+        if ($Config.Apps -isnot [string] -and $Config.Apps -isnot [System.Collections.IEnumerable]) {
+            return 'Configuration Apps entries must be strings.'
+        }
+        foreach ($app in @($Config.Apps)) {
+            if ($app -isnot [string]) {
+                return 'Configuration Apps entries must be strings.'
+            }
+        }
+    }
+
+    foreach ($categoryName in @('Tweaks', 'Deployment')) {
+        $category = $Config.$categoryName
+        if ($null -eq $category) { continue }
+
+        if ($category -is [string] -or $category -isnot [System.Collections.IEnumerable]) {
+            return "Configuration $categoryName entries must contain Name and Value properties."
+        }
+        foreach ($setting in @($category)) {
+            $hasName = if ($setting -is [System.Collections.IDictionary]) { $setting.Contains('Name') } else { $null -ne $setting.PSObject.Properties['Name'] }
+            $hasValue = if ($setting -is [System.Collections.IDictionary]) { $setting.Contains('Value') } else { $null -ne $setting.PSObject.Properties['Value'] }
+            if (-not $setting -or -not $hasName -or -not $hasValue -or $setting.Name -isnot [string] -or [string]::IsNullOrWhiteSpace($setting.Name)) {
+                return "Configuration $categoryName entries must contain Name and Value properties."
+            }
+        }
+    }
+
+    $lookup = @{}
+    foreach ($setting in @($Config.Deployment)) {
+        if ($setting -and $setting.Name) {
+            $lookup[$setting.Name] = $setting.Value
+        }
+    }
+
+    $hasScope = $lookup.ContainsKey('AppRemovalScopeIndex')
+    $hasUser = $lookup.ContainsKey('UserSelectionIndex')
+
+    $scopeIndex = $null
+    if ($hasScope) {
+        if (-not [int]::TryParse("$($lookup['AppRemovalScopeIndex'])", [ref]$scopeIndex) -or $scopeIndex -notin @(0, 1, 2)) {
+            return 'AppRemovalScopeIndex must be a supported numeric value (0, 1, or 2).'
+        }
+    }
+
+    $userIndex = $null
+    if ($hasUser) {
+        if (-not [int]::TryParse("$($lookup['UserSelectionIndex'])", [ref]$userIndex) -or $userIndex -notin @(0, 1, 2)) {
+            return 'UserSelectionIndex must be a supported numeric value (0, 1, or 2).'
+        }
+    }
+
+    # "Current user only" (index 1) is only valid together with "Current User" (index 0)
+    if ($hasScope -and $scopeIndex -eq 1) {
+        if (-not $hasUser -or $userIndex -ne 0) {
+            return "App removal scope 'Current user only' (AppRemovalScopeIndex 1) requires the deployment target 'Current User' (UserSelectionIndex 0)."
+        }
+    }
+
+    # "Target user only" (index 2) is only valid together with "Other User" (index 1)
+    if ($hasScope -and $scopeIndex -eq 2) {
+        if (-not $hasUser -or $userIndex -ne 1) {
+            return "App removal scope 'Target user only' (AppRemovalScopeIndex 2) requires the deployment target 'Other User' (UserSelectionIndex 1)."
+        }
+        if (-not $lookup.ContainsKey('OtherUsername') -or [string]::IsNullOrWhiteSpace("$($lookup['OtherUsername'])")) {
+            return "App removal scope 'Target user only' (AppRemovalScopeIndex 2) requires an 'OtherUsername' value."
+        }
+    }
+
+    return $null
+}