[Bug]: NeverOOM sometimes crashes the generation

### Checklist

- [X] The issue exists after disabling all extensions
- [X] The issue exists on a clean installation of webui
- [ ] The issue is caused by an extension, but I believe it is caused by a bug in the webui
- [X] The issue exists in the current version of the webui
- [ ] The issue has not been reported before recently
- [X] The issue has been reported before but has not been fixed yet

### What happened?

NeverOOM options result in either
`RuntimeError: Expected all tensors to be on the same device, but found at least two devices, cuda:0 and cpu!`
or
`TypeError: 'NoneType' object is not iterable`

### Steps to reproduce the problem

1. Enable All/One of NeverOOM options (especially tiled vae)
2. Watch the generation crash
3. With disabled tiled vae try generating an XYZ grid with model changes

### What should have happened?

Generation shouldn't crash

### What browsers do you use to access the UI ?

Google Chrome, Microsoft Edge

### Sysinfo

[sysinfo-2024-03-04-12-41.json](https://github.com/lllyasviel/stable-diffusion-webui-forge/files/14481577/sysinfo-2024-03-04-12-41.json)

### Console logs

```Shell
https://paste.ee/p/DFdks
```

### Additional information

_No response_

Start by reproducing the crash with the NeverOOM options, especially tiled VAE, and then with an XYZ grid after disabling tiled VAE. Review the linked console log and sysinfo for the reported device-mismatch and NoneType errors; done means generation completes without either crash.

Written by the indexing model from the issue text.