TypeError: undefined is not an object (evaluating 'i.key.length')

## Error

```
undefined is not an object (evaluating 'i.key.length')
```

## Stack trace

```
../node_modules/@codemirror/autocomplete/dist/index.js:1260 in commitCharacters.keydown
../node_modules/@codemirror/view/dist/index.js:4327 in handler
../node_modules/@codemirror/view/dist/index.js:4218 in InputState.runHandlers
../node_modules/@codemirror/view/dist/index.js:4208 in InputState.handleEvent
../node_modules/@sentry/browser/src/helpers.ts:117 in sentryWrapped
```

## Tracking Details
- **Project**: exercism-js
- **Sentry**: [TypeError: undefined is not an object (evaluating 'i.key.length')](https://thalamus-ai.sentry.io/issues/98481411/)
- **Culprit**: commitCharacters.keydown(@codemirror/autocomplete/dist/index)
- **First seen:** Feb 23, 2026