Open3DViewer throw exception when user push ESC key.

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### Describe the issue

I'm using open3d 0.14.1 c++ (release) and checking the implementation concept of open3d viewer.
and I can see through the following function which seems intended to close window when user put escape key.

- Window::OnKeyEvent(const KeyEvent& e)

but when I put the key after showing the window frame, I can see the following exception.

and the following image is the final application code which occur exception

### Steps to reproduce the bug

```python
you can reproduce this issue with the following step.

1. execute open3dviewer.exe
2. wait until window is loaded.
3. put escape key.
4. the exception will be checked when you using debug mode.
```

### Error message


### Expected behavior

window should be closed and program need to be shut down.

### Open3D, Python and System information

```markdown
- Operating system: Windows 11 64-bit
- Python version: Python 3.7.8
- Open3D version: 0.14.1+0a49cdf79
- System architecture: x64
- Is this a remote workstation?: no
- How did you install Open3D?: build from source
- Compiler version (if built from source): C/C++ Optimizing Compiler Version 19.29.30141 for x86
```

### Additional information

_No response_