Getting "[object Object]" in background image url

Hi all,

I created new phoenix project, and then added vuejs to it. Vue library loads successfully. But when I set background-image: url('../static/images/test.svg') in my app.css, I didn’t see background image in the result.

I inspected the output html in my browser and it seems that, the file-loader or css-loader sets invalid path in generated css. The background-image value is url([object Object]).

Here is my webpack.config.js file:

const path = require('path');
const glob = require('glob');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const TerserPlugin = require('terser-webpack-plugin');
const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');
const CopyWebpackPlugin = require('copy-webpack-plugin');
const VueLoaderPlugin = require('vue-loader/lib/plugin');

module.exports = (env, options) => ({
	optimization: {
		minimizer: [
			new TerserPlugin({ cache: true, parallel: true, sourceMap: false }),
			new OptimizeCSSAssetsPlugin({})
		]
	},
	entry: {
		'./js/app.js': glob.sync('./vendor/**/*.js').concat(['./js/app.js'])
	},
	output: {
		filename: 'app.js',
		path: path.resolve(__dirname, '../priv/static/js')
	},
	module: {
		rules: [
			{
				test: /\.js$/,
				exclude: /node_modules/,
				use: {
					loader: 'babel-loader'
				}
			},
			{
				test: /\.vue$/,
				loader: 'vue-loader'
			},
			{
				test: /\.css$/,
				use: [MiniCssExtractPlugin.loader, 'css-loader']
			},
			{
				test: /\.(png|svg|jpg|jpeg|gif|woff|woff2|ttf|eot)$/,
				loader: 'url-loader'
			},
		]
	},
	plugins: [
		new MiniCssExtractPlugin({ filename: '../css/app.css' }),
		new CopyWebpackPlugin([{ from: 'static/', to: '../' }]),
		new VueLoaderPlugin()
	]
});