TypeError: Cannot read properties of null (onKeyDown.js)

## Description

Greetings dear fellows.

We did set up Algolia search autocomplete with the help of `@algolia/autocomplete-js`. It is quite similar to what is defined in the [query suggestions sandbox example](https://codesandbox.io/p/sandbox/github/algolia/autocomplete/tree/next/examples/query-suggestions?file=%2Fapp.tsx) from your docs.

It is rolled out in one of our services and works, however we are noticing cryptic errors coming from the library code.
We cannot reproduce it and it happens quite occasionally.
Sentry gives us the following traceback:

```
TypeError: Cannot read properties of null (reading 'item')
at (./node_modules/@algolia/autocomplete-core/dist/esm/onKeyDown.js:116:20)
at .onKeyDown(./node_modules/@algolia/autocomplete-core/dist/esm/getPropGetters.js:179:9)
at .onKeyDown(./node_modules/@algolia/autocomplete-js/dist/esm/elements/Input.js:36:18)
at eventProxy(./node_modules/@algolia/autocomplete-js/dist/esm/utils/setProperties.js:30:25)
```

## Reproduction

Couldn't yet.

## Expected behavior

No errors coming from the library.

## Environment

- OS: Windows >= 10
- Browser: Edge 122.0.0, Firefox 124.0, Chrome 122.0.0, Edge 120.0.0
- Autocomplete version: 1.17.0

Start by inspecting autocomplete-core/dist/esm/onKeyDown.js around line 116 and trace the onKeyDown flow through getPropGetters.js and autocomplete-js/dist/esm/elements/Input.js. Determine when the selected item is null, then verify the fix against the reported browsers and add regression coverage if the repository provides a relevant test entry point.

Written by the indexing model from the issue text.