fix: extract_msg.Message resource leak in _convert_msg_to_pdf bei pisa-Exception

Ressource wird jetzt per try/finally garantiert geschlossen, auch wenn
pisa.CreatePDF eine Exception wirft. Explizite msg.close()-Aufrufe entfernt.
Zwei neue Tests: close() bei Fehler und close() bei Erfolg.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Lukas Geiger

UniversalInvoiceMail.py

@@ -3500,6 +3500,7 @@ def _convert_msg_to_pdf(self, msg_path: Path) -> Optional[Path]:
                 )
             return None
 
+        msg = None
         try:
             msg = extract_msg.Message(str(msg_path))
             html_body = msg.htmlBody
@@ -3509,7 +3510,6 @@ def _convert_msg_to_pdf(self, msg_path: Path) -> Optional[Path]:
                 html_body = html_body.decode("utf-8", errors="replace")
 
             if not html_body:
-                msg.close()
                 return None
 
             pdf_path = msg_path.with_suffix(".pdf")
@@ -3518,16 +3518,19 @@ def _convert_msg_to_pdf(self, msg_path: Path) -> Optional[Path]:
                     pisa.CreatePDF(html_body, dest=f)
                 if hasattr(self, 'log_output'):
                     self.log_output.appendPlainText(f"[MSG] Konvertiert: {msg_path.name} -> {pdf_path.name}")
-                msg.close()
                 return pdf_path
-            else:
-                msg.close()
-                return None
+            return None
 
         except Exception as e:
             if hasattr(self, 'log_output'):
                 self.log_output.appendPlainText(f"[MSG] Fehler bei {msg_path.name}: {e}")
             return None
+        finally:
+            if msg is not None:
+                try:
+                    msg.close()
+                except Exception:
+                    pass
 
     def scan_folders_for_new_files(self) -> int:
         """

test_helpers.py

@@ -685,5 +685,63 @@ def _save_attachment_invoice(self, **kwargs):
         self.assertNotIn("< 50", body, "Raw < must not appear in IMAP merge body_html")
 
 
+class TestMsgConvertClosesMessage(unittest.TestCase):
+    """_convert_msg_to_pdf() muss extract_msg.Message auch im Fehlerfall schliessen."""
+
+    def _make_mock_msg(self, plain_body: str = "Test"):
+        mock_msg = MagicMock()
+        mock_msg.htmlBody = None
+        mock_msg.body = plain_body
+        return mock_msg
+
+    def test_msg_closed_on_pisa_exception(self):
+        from UniversalInvoiceMail import MainWindow
+
+        mock_msg = self._make_mock_msg()
+        mock_extract_msg = MagicMock()
+        mock_extract_msg.Message.return_value = mock_msg
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            msg_path = Path(tmpdir) / "test.msg"
+            msg_path.write_bytes(b"dummy")
+
+            win = MainWindow.__new__(MainWindow)
+
+            with patch.dict("sys.modules", {"extract_msg": mock_extract_msg}), \
+                 patch("UniversalInvoiceMail.XHTML2PDF_AVAILABLE", True), \
+                 patch("UniversalInvoiceMail.pisa") as mock_pisa:
+                mock_pisa.CreatePDF.side_effect = RuntimeError("pisa crash")
+                result = win._convert_msg_to_pdf(msg_path)
+
+        self.assertIsNone(result)
+        mock_msg.close.assert_called_once()
+
+    def test_msg_closed_on_success(self):
+        from UniversalInvoiceMail import MainWindow
+
+        mock_msg = self._make_mock_msg()
+        mock_extract_msg = MagicMock()
+        mock_extract_msg.Message.return_value = mock_msg
+
+        with tempfile.TemporaryDirectory() as tmpdir:
+            msg_path = Path(tmpdir) / "test.msg"
+            msg_path.write_bytes(b"dummy")
+
+            win = MainWindow.__new__(MainWindow)
+
+            def fake_create_pdf(html, dest, **kwargs):
+                dest.write(b"%PDF-1.4 fake")
+                return MagicMock(err=0)
+
+            with patch.dict("sys.modules", {"extract_msg": mock_extract_msg}), \
+                 patch("UniversalInvoiceMail.XHTML2PDF_AVAILABLE", True), \
+                 patch("UniversalInvoiceMail.pisa") as mock_pisa:
+                mock_pisa.CreatePDF.side_effect = fake_create_pdf
+                result = win._convert_msg_to_pdf(msg_path)
+
+        mock_msg.close.assert_called_once()
+        self.assertIsNotNone(result)
+
+
 if __name__ == "__main__":
     unittest.main()