How do I configure LESS with Aurelia ESnext Easy-Webpack? - less

Question

I'm trying to configure Less CSS support in the Aurelia ESnext-Webpack Skeleton starter kit, and having pulled in a Less-based framework, I'm seeing the following warning when I run npm start:
WARNING in ./~/css-loader!./~/spectre.css/spectre.less
Module build failed: Unknown word (1:1)
> 1 | // Copyright 2016 Spectre.css
| ^
2 | // Licensed under MIT Open Source
3 |
4 | // Core variables
# ./src ^\.\/.*$
# ./~/aurelia-loader-webpack/dist/commonjs/aurelia-loader-webpack.js
# multi aurelia
Here's the configuration I'm using:
/* ./webpack.config.babel.js */
...
import html from '#easy-webpack/config-html'
import less from '#easy-webpack/config-less'
import css from '#easy-webpack/config-css'
...
let config = generateConfig(
...
html(),
less({ filename: 'styles.css', allChunks: true, sourceMap: false }),
css({ filename: 'styles.css', allChunks: true, sourceMap: false }),
...
)
...
However, despite the warning it appears to be working - styles.css contains all of the less assets when inspected in the browser.
Have I configured easy-webpack/config-less correctly?
If so, how do stop the warning message from showing?