TypeError: null is not an object (evaluating 'context.document.currentPage')
i run `npm install` ,and then run `npm run render`,but throw this error 

npm 4.5.0
node 7.8.0
sketch 0.43.2

```
npm run render

> profile-cards@ render /Users/yutou/code/react-sketchapp/examples/profile-cards
> skpm build --watch --run

🖨  Copied src/manifest.json in 9ms
Executing post-build scripts
🔩  Built ./main.js in 1451ms
TypeError: null is not an object (evaluating 'context.document.currentPage')
line: 6740
column: 104
```