TwigException: Cannot extend an inline template.
Not sure if this is the correct place.

I try to use twig.js with koa 2:

```js
const Views = require('koa-views');

app.use(Views('./views', {
	map: {
		twig: 'twig'
	},
	extension: 'twig'
}));

app.use(Route.get('/', async(ctx) => {
	await ctx.render('pages/home');
}));
```

Now i'll try to use a layout

layout.twig:
```html
<!DOCTYPE html>
<html>

<head>
	<meta charset="utf-8" />
	<title>Hello World!</title>
</head>

<body>
	{% block body %}{% endblock %}
</body>

</html>
```

home.twig
```html
{% extends "../layout.twig" %}

{% block body %}
    Hello World
{% endblock %}
```

Now i'm getting this error:
```
Error parsing twig template undefined:
TwigException: Cannot extend an inline template.

  Error: non-error thrown: TwigException: Cannot extend an inline template.
      at Object.onerror (C:\Users\jerom\Documents\programming\test\node_modules\koa\lib\context.js:107:40)
      at onerror (C:\Users\jerom\Documents\programming\test\node_modules\koa\lib\application.js:133:34)
```

Anyone an idea what i did wrong here?