Seems to be broken with latest preact-cli (3.0.0-rc6)

preact build output:

```
✖ ERROR Error: TypeError: Cannot read property 'filter' of undefined
```
at ode_modules/preact-cli-plugin-async/dist/async-plugin.js:1:51

Which corresponds to this:

```js
module.exports=function(e){var r=e.module.loaders.filter
```

Could be the change from webpack 3 to 4.