React's strict mode runs effects twice on mount, but once it's done that
it'll go forward with the state from the first effect. For example, this
component:
```tsx
let nextId = 1
function Component() {
const [state, setState] = useState(null)
useEffect(() => {
const id = nextId++
console.log('set up', id)
setState(id)
return () => console.log('tear down', id)
}, [])
if (!state) return
console.log('render', state)
}
```
Would log something like this when mounting for the first time:
- `set up 1`
- `tear down 1`
- `set up 2`
- `render 1`
For us, this is a problem: editor 2 is the version that's still running,
but editor 1 is getting used for render. React talks a bit about this
issue here: https://github.com/reactwg/react-18/discussions/19
The fix seems to be to keep the editor in a `useRef` instead of a
`useState`. We need the state to trigger re-renders though, so we sync
the ref into the state although we don't actually use the state value.
### Change Type
- [x] `sdk` — Changes the tldraw SDK
- [x] `bugfix` — Bug fix
### Release Notes
- Fix a bug causing text shape measurement to work incorrectly when
using react strict mode
2d2a7ea76f