TypeError: Cannot read properties of undefined (reading 'startsWith')

We are observing a `TypeError` from this line:

```.ts
const elideShift = event.code.startsWith('Key') && event.shiftKey && event.key.toUpperCase() === event.key;
```

See: [Sentry](https://sentry.io/organizations/github/issues/?project=1890375&query=is%3Aunresolved+github%2Fhotkey&sort=new&statsPeriod=1h)

Though this was first seen 9 months ago, looks like there has been a recent spike.

Use the reported event.code.startsWith line as the entry point; trace how keyboard events reach it and determine why event.code can be undefined. Confirm the expected handling with a reproduction or regression test for the reported case, and verify that it no longer throws a TypeError.

Written by the indexing model from the issue text.