File named `DUMMY` appears when accepting a code fix

1. Open a new file in VSCode (`Ctrl+N`). Do not save it.
2. Set the language to Bicep (`Ctrl+Shift+P` - Change Language Mode)
3. Enter the following:
```bicep
var test = {
foo: 'string' /* foo */
}
```
4. Put the cursor on `'string'`, and press `Ctrl+.`
5. Accept the "Extract variable" suggestion
6. DUMMY:

It's not very nice of VSCode to insult my intelligence 😢

Reproduce the issue in a new unsaved VSCode file using Bicep, then trigger the Ctrl+. “Extract variable” suggestion on the shown expression. Trace the code-fix path responsible for the generated file name; done means accepting the fix no longer creates or displays a file named “DUMMY”.

Written by the indexing model from the issue text.