diff --git a/FluentCleaner/Services/AiExplainer.cs b/FluentCleaner/Services/AiExplainer.cs
index 2bd5c38..b06d3af 100644
--- a/FluentCleaner/Services/AiExplainer.cs
+++ b/FluentCleaner/Services/AiExplainer.cs
@@ -53,7 +53,7 @@ public static async Task<string> ExplainAsync(CleanerEntry entry)
 
             if (root.TryGetProperty("error", out var err))
             {
-                var msg = err.TryGetProperty("message", out var m) ? m.GetString() : "Unknown error";
+                var msg = err.TryGetProperty("message", out var m) ? m.GetString() ?? "Unknown error" : "Unknown error";
                 return ResourceService.Fmt("AI_ApiError", msg);
             }
 
diff --git a/FluentCleaner/Views/NewCleanerDialog.xaml.cs b/FluentCleaner/Views/NewCleanerDialog.xaml.cs
index e7285cc..a85e766 100644
--- a/FluentCleaner/Views/NewCleanerDialog.xaml.cs
+++ b/FluentCleaner/Views/NewCleanerDialog.xaml.cs
@@ -44,7 +44,7 @@ public NewCleanerDialog(CustomEntryVm? existing)
     // --- Event handlers --------------------------------------------------
     private void TypeBtn_Click(object sender, RoutedEventArgs e)
     {
-        var isPs1 = sender == btnPs1;
+        var isPs1 = ReferenceEquals(sender, btnPs1);
         btnIni.IsChecked = !isPs1;
         btnPs1.IsChecked =  isPs1;
     }