Getting error while using "extract-text-webpack-plugin" with webpack : "Module build failed: Error: Parameter 'dependency' must be a Dependency" - npm

Question

Error while running webpack-dev-server
ERROR in ./css/app.scss
Module build failed: Error: Parameter 'dependency' must be a Dependency
at Compilation.process [as _addModuleChain] (/usr/local/lib/node_modules/webpack-dev-server/node_modules/webpack/lib/Compilation.js:347:9)
at Compilation.process [as addEntry] (/usr/local/lib/node_modules/webpack-dev-server/node_modules/webpack/lib/Compilation.js:423:7)
at SingleEntryPlugin.<anonymous> (/Users/roshankarki/Desktop/del_del/wp_tst/node_modules/webpack/lib/SingleEntryPlugin.js:22:15)
at Compiler.applyPluginsParallel (/usr/local/lib/node_modules/webpack-dev-server/node_modules/webpack/node_modules/tapable/lib/Tapable.js:107:14)
at Compiler.compile (/usr/local/lib/node_modules/webpack-dev-server/node_modules/webpack/lib/Compiler.js:394:7)
at Compiler.runAsChild (/usr/local/lib/node_modules/webpack-dev-server/node_modules/webpack/lib/Compiler.js:203:7)
at Object.module.exports.pitch (/Users/roshankarki/Desktop/del_del/wp_tst/node_modules/extract-text-webpack-plugin/loader.js:81:18)
webpack: bundle is now VALID.
My webpack.config.js looks like this:
var path = require('path');
var ExtractTextPlugin = require("extract-text-webpack-plugin");
module.exports = {
/* this defins path where entry files are to be found */
context: path.resolve('js'),
entry: ["./utils","./app"],
output: {
/* this is output directory of bundle.js */
path: path.resolve('build/'),
/* this is path of directory where bundle will be served in server */
publicPath: '/public/assets/',
filename: "bundle.js"
},
/* this plugin helps to generate seperate styles.css file rather in once single bundle.js file */
plugins: [
new ExtractTextPlugin("styles.css")
],
/* when server is loaded it tells where to look for index file accessed from root */
devServer: {
contentBase: 'public'
},
module: {
preLoaders: [
{
test: /\.js$/,
exclude: /node_modules/,
loader: "jshint-loader"
}
],
loaders: [
{
test: /\.es6$/,
exclude: /node_modules/,
loader: "babel-loader"
},
{
test: /\.css$/,
exclude: /node_modules/ ,
loader: ExtractTextPlugin.extract("style-loader", "css-loader")
},
{
test: /\.scss$/,
exclude: /node_modules/ ,
loader: ExtractTextPlugin.extract("style-loader", "css-loader!sass-loader")
}
]
},
/* this will resolve file in common js style require without extension */
resolve: {
extensions: ['', '.js', '.es6']
},
watch: true
}
Before using this plugin everything was working fine. As i intend to output different bundle for css, i need to fix this issue.
Found issue in github but it did not help:
https://github.com/webpack/extract-text-webpack-plugin/issues/132

Answer 1

well updating node worked for me. I did this by running "brew update" and "brew upgrade" command, as i am using homebrew as a package manage in mac.
Following instruction in the git link provide in my question resulted in error as i was installing webpack and webpack-dev-server globally. I removed it and only had local copy which did the trick at the end.
command to list global copy of node modules installed:
npm list -g --depth=0
I use this command to remove global copy:
npm uninstall -g {replace_with_package_name}
command to check local copy:
npm list --depth=0