Error: Canceled future for history_request message before replies were done

## Description

The following message is logged to the dev tools console when creating a new console:

```
Error: Canceled future for history_request message before replies were done
```


## Reproduce

1. Open RetroLab, for example with this gist: https://gist.github.com/jtpio/4a6a34da66b32249e28df718ec30e4d7
2. Click on "New Console"
3. Open the dev tools console
4. See the error message

## Expected behavior

There should not be any error message when opening a new console.

The message is not reallt harmful since the console widget is opened in a different browser tab. But it would still be nice to fix.

## Context

Follow-up to jupyter/retrolab#197

This is most likely coming from this line:

https://github.com/jupyterlab/retrolab/blob/f5507c408dc7613d3c04c3df0c56c660790a846b/packages/console-extension/src/index.ts#L69

Start at packages/console-extension/src/index.ts around line 69, which the report identifies as the likely source of the message. Reproduce it by opening RetroLab, creating a new console, and checking the browser dev tools console. Done means opening a new console no longer logs the canceled future error.

Written by the indexing model from the issue text.