Workflow does not load when nodes are missing, so the workflow cannot be fixed in the UI.

### Prerequisites

- [x] I am running the latest version of ComfyUI
- [x] I have searched existing issues to make sure this isn't a duplicate
- [x] I have tested with all custom nodes disabled ([see how](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled))

### What happened?

When loading a workflow with missing nodes, well, it won't load.
The nodes are not public.
In fact, I changed the name, that is why they will not load.
I'd expect the workflow to load inside the UI like it used to, with the bad nodes outlined in red or such, so you can fix them without a text editor, which itself would probably cause errors and linkage problems if not meticulously edited by hand.
This happens with the file picker or with drag and drop.

The workflow is an API workflow

### Steps to Reproduce

1. Load a workflow with missing nodes, and get rejected.
2.
3.

[wan_2_1_infinite_talk_tool.json](https://github.com/user-attachments/files/23159949/wan_2_1_infinite_talk_tool.json)

### How is this affecting you?

Feature doesn't work as expected

### ComfyUI Frontend Version

1.28.7

### Browser

Chrome/Chromium

### Console Errors

```javascript
none
```

### Logs

```shell

```

### Additional Context

_No response_

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-6328-Workflow-does-not-load-when-nodes-are-missing-so-the-workflow-cannot-be-fixed-in-the--2996d73d3650814d8eaaf9bca4062b85) by [Unito](https://www.unito.io)