Error with including loaders in webpack.config.js

I am trying to integrate a third party angular component into an Ionic 3 demo application.

That angular component is having HTML, CSS & SCSS inside, so I've modified my webpack.config.js to include loaders.

This has created two problems for me:

1. "Object prototype may only be an Object or null: undefined"
2. Sass Error: File to import not found or unreadable: ~bootstrap/scss/mixins

My webpack.config.js

var path = require('path');
var webpack = require('webpack');
var ionicWebpackFactory = require(process.env.IONIC_WEBPACK_FACTORY);

var ModuleConcatPlugin = require('webpack/lib/optimize/ModuleConcatenationPlugin');
var PurifyPlugin = require('@angular-devkit/build-optimizer').PurifyPlugin;

var optimizedProdLoaders = [
  {
    test: /\.json$/,
    loader: 'json-loader'
  },
  {
    test: /\.js$/,
    loader: [
      {
        loader: process.env.IONIC_CACHE_LOADER
      },

      {
        loader: '@angular-devkit/build-optimizer/webpack-loader',
        options: {
          sourceMap: true
        }
      },
    ]
  },
  {
    test: /\.ts$/,
    loader: [
      {
        loader: process.env.IONIC_CACHE_LOADER
      },

      {
        loader: '@angular-devkit/build-optimizer/webpack-loader',
        options: {
          sourceMap: true
        }
      },

      {
        loader: process.env.IONIC_WEBPACK_LOADER
      }
    ]
  }
];

function getProdLoaders() {
  if (process.env.IONIC_OPTIMIZE_JS === 'true') {
    return optimizedProdLoaders;
  }
  return devConfig.module.loaders;
}

var devConfig = {
  entry: process.env.IONIC_APP_ENTRY_POINT,
  output: {
    path: '{{BUILD}}',
    publicPath: 'build/',
    filename: '[name].js',
    devtoolModuleFilenameTemplate: ionicWebpackFactory.getSourceMapperFunction(),
  },
  devtool: process.env.IONIC_SOURCE_MAP_TYPE,

  resolve: {
    extensions: ['.ts', '.js', '.json'],
    modules: [path.resolve('node_modules')]
  },

  module: {
    loaders: [
      {
        test: /\.json$/,
        loader: 'json-loader'
      },
      {
        test: /\.ts$/,
        loader: process.env.IONIC_WEBPACK_LOADER
      },
      {
        test: /\.css$/,
        loader: 'css-loader'
      },
      {
        test: /\.scss$/,
        loaders: [
          'style-loader',
          'css-loader',
          'sass-loader',
          {
            loader: 'sass-resources-loader',
            options: {
              resources: 'node_modules/@plentymarkets/terra-components/app/assets/styles/_variables.scss'
            }
          }
        ]
      },
      {
        test: /\.html$/,
        loader: 'html-loader'
      }
    ]
  },

  plugins: [
    ionicWebpackFactory.getIonicEnvironmentPlugin(),
    ionicWebpackFactory.getCommonChunksPlugin()
  ],

  // Some libraries import Node modules but don't use them in the browser.
  // Tell Webpack to provide empty mocks for them so importing them works.
  node: {
    fs: 'empty',
    net: 'empty',
    tls: 'empty'
  }
};

var prodConfig = {
  entry: process.env.IONIC_APP_ENTRY_POINT,
  output: {
    path: '{{BUILD}}',
    publicPath: 'build/',
    filename: '[name].js',
    devtoolModuleFilenameTemplate: ionicWebpackFactory.getSourceMapperFunction(),
  },
  devtool: process.env.IONIC_SOURCE_MAP_TYPE,

  resolve: {
    extensions: ['.ts', '.js', '.json'],
    modules: [path.resolve('node_modules')]
  },

  module: {
    loaders: getProdLoaders()
  },

  plugins: [
    ionicWebpackFactory.getIonicEnvironmentPlugin(),
    ionicWebpackFactory.getCommonChunksPlugin(),
    new ModuleConcatPlugin(),
    new PurifyPlugin()
  ],

  // Some libraries import Node modules but don't use them in the browser.
  // Tell Webpack to provide empty mocks for them so importing them works.
  node: {
    fs: 'empty',
    net: 'empty',
    tls: 'empty'
  }
};


module.exports = {
  dev: devConfig,
  prod: prodConfig
}

Is there anything wrong with the loaders in my webpack.config.js?

Please let me know if there is such.

Thanks in advance.

The "issue Object prototype may only be an Object or null: undefined" is related with not using a compatible angular version, you might be using terra components with version 5 of angular. Downgrade angular version to 4 and check if the error still exists.

Another issue "Sass Error: File to import not found or unreadable: ~bootstrap/scss/mixins" is with sass-loader. sass-loader usually detects ~ and searches in the node modules for the same. In this case sass-loader is not recognizing it and it is throwing an error. Change ~ to node_modules and check if error is still present. For more info about this issue check https://github.com/webpack-contrib/sass-loader