diff --git a/src/ui/MainWindow.py b/src/ui/MainWindow.py
index 58cfb05..16a984d 100644
--- a/src/ui/MainWindow.py
+++ b/src/ui/MainWindow.py
@@ -891,7 +891,7 @@ class MainWindow(QMainWindow):
 
                 # Transformations-Aktionen (nur aktiv wenn XML-Dateien vorhanden)
                 tree_node_obj = item.data(0, Qt.ItemDataRole.UserRole) if item else None
-                has_xml_files = tree_node_obj and self._has_xml_files_recursive(tree_node_obj)
+                has_xml_files = bool(tree_node_obj and self._has_xml_files_recursive(tree_node_obj))
 
                 action_transform = QAction("Alle XML-Dateien transformieren", self)
                 action_transform.setIcon(QIcon(QIcon.fromTheme("system-run")))
@@ -3714,9 +3714,9 @@ class MainWindow(QMainWindow):
         Returns:
             bool: True wenn erfolgreich, False bei Fehler
         """
+        pdf_basename = diff_pdf_path.name  # Initialisiere am Anfang für Exception-Handler
+        
         try:
-            pdf_basename = diff_pdf_path.name
-
             # Prüfe ob new-PDF existiert
             if not new_pdf_path.exists():
                 logger.warning(f"New-PDF nicht gefunden: {pdf_basename}")
@@ -3738,7 +3738,11 @@ class MainWindow(QMainWindow):
 
             # Diff-Icon beim XML-Knoten entfernen
             # WICHTIG: xml_item_map verwendet relative Pfade, nicht absolute!
-            xml_relative_path = xml_file_path.relative_to(self.project.project_dir)
+            if self.project and self.project.project_dir:
+                xml_relative_path = xml_file_path.relative_to(self.project.project_dir)
+            else:
+                # Fallback: Verwende absoluten Pfad als String
+                xml_relative_path = xml_file_path
             map_key = f"{xml_relative_path}|{xsl_id_str}"
             if map_key in self.xml_item_map:
                 tree_item = self.xml_item_map[map_key]