Blank dashboard2 sidebar

### Current Behavior

We have an instance on FFC where the dashboard sidebar is blank:

And the following error in the console:

```
VM75:1686 Uncaught TypeError: Cannot read properties of undefined (reading 'surface')
at Object.addItem (:1686:113)
at V...insertItemAt (red.min.js?v=6cba03f1db65:18:29496)
at a. [as insertItemAt] (vendor.js?v=6cba03f1db65:10:1122)
at V...addItem (red.min.js?v=6cba03f1db65:18:29695)
at a. [as addItem] (vendor.js?v=6cba03f1db65:10:1122)
at HTMLOListElement. (vendor.js?v=6cba03f1db65:10:2133)
at S.each (vendor.js?v=6cba03f1db65:2:2976)
at s.fn.init.each (vendor.js?v=6cba03f1db65:2:1454)
at V.fn. [as editableList] (vendor.js?v=6cba03f1db65:10:1951)
at :1699:22
```

This is a customer's instance; don't have a lot else to go on. Originally we thought it may be a clash with dashboard 1.0 which that had installed - but we removed it and reloaded the editor to the same result.

There were a couple misconfigured `ui-group` nodes (missing their page config) and a couple dashboard nodes without a `ui-group` selected - but we tidied that all up and reloaded (in case of any residual state), but the error remains.

### Expected Behavior

_No response_

### Steps To Reproduce

_No response_

### Environment

- Dashboard version: 1.23
- Node-RED version: 4.x

### Have you provided an initial effort estimate for this issue?

I have provided an initial effort estimate