Loft (ruled surface + closed) + Mirror causes broken model geometry

### Problem description

When I do a loft between 3 sketches, then I mirror it, and then I toggle multiple times "Ruled surface" and "Closed" in the loft parameters, the model geometry starts breaking.

### Workbench affected?

Part Design

### Steps to reproduce

The issue happens at 1:39:

https://github.com/user-attachments/assets/0587f190-2c30-4ae6-9371-776aa5edfcbb

The macro wouldn't replay properly, but I figured it might help anyway:

[reproduce_bug.FCMacro.zip](https://github.com/user-attachments/files/27085529/reproduce_bug.FCMacro.zip)

Resulting file:

[loft_mirror_bug.zip](https://github.com/user-attachments/files/27085526/loft_mirror_bug.zip)

### Expected behavior

I'm not sure what the "closed" toggle in loft does, but if I toggle it multiple times and leave it disabled I expect to get the same result as if I've never enabled it.

### Actual behavior

The model geometry breaks and I didn't find a way to fix it after this happens.

### Development version About Info (in Safe Mode)

```shell
OS: NixOS 26.05 (Yarara) (niri/wayland)
Architecture: x86_64
Version: 1.2.0dev.20260421 (Git shallow) AppImage
Build date: 2026/04/21 23:21:45
Build type: Release
Branch: (HEAD detached at 449725202)
Hash: 449725202d0ab581516aacad59d62cdce80db82a
Python 3.11.14, Qt 6.8.3, Coin 4.0.8, Vtk 9.3.1, boost 1_86, Eigen3 3.4.0, PySide 6.8.3
shiboken 6.8.3, xerces-c 3.3.0, IfcOpenShell 0.8.2, OCC 7.8.1
Locale: English/United States (en_US)
Stylesheet/Theme/QtStyle: FreeCAD.qss/FreeCAD Dark/
Navigation Style/Orbit Style/Rotation Mode: Blender/Rounded Arcball/Window center
Logical DPI/Physical DPI/Pixel Ratio: 96/91.7275/1
```

### Last known good version (optional)

```shell

```