There is currently a bug when using sourceMap with css-loader. Removing sourceMap from your css loader should fix it.
"module": {
"loaders": [
{
"test": /\.scss$/,
"loaders": ["style", "css", "sass?sourceMap"]
},
{
test: /\.jpg$/,
loader: "file-loader"
}
]
}
Issue is related to: https://github.com/webpack/css-loader/issues/296