Generation Previews not showing in subgraph node.

### Prerequisites

- [x] I am running the latest version of ComfyUI
- [x] I have custom nodes enabled

### What happened?

Occasionally I can right click a subgraph, edit widgets, and unhide the vlatentpreview and it will work, but most of the time nothing happens, the node will also resize itself as if it was trying to resize for the preview.

Opening the subgraph to edit the nodes inside I can see the preview running on the sampler most of the time, but occasionally nothing is shown at all. I have "live preview method" set to latent2rgb.

### Steps to Reproduce

1. Open workflow with subgraph
2. click Run
3. See no preview?

### How is this affecting you?

Crashes ComfyUI completely

### ComfyUI Frontend Version

1.47.11

### Browser

Firefox

### Console Errors

```javascript
n/a
```

### Logs

```shell

```

### Additional Context

_No response_

Start by reproducing the issue in ComfyUI_frontend 1.47.11 with a workflow containing a subgraph, Firefox, and the latent2rgb live preview method. Compare running the sampler inside the subgraph with the preview exposed on the subgraph node, and capture the conditions that cause the node to resize, show no preview, or crash ComfyUI. Done means generation previews reliably appear without crashing.

Written by the indexing model from the issue text.