Sample webpack configuration to demonstrate a non-descriptive error message for an incorrect "dependencies"

build__base.js

module.exports = {
  context: `${__dirname}/../js`,
  output: {
    pathinfo: true,
    filename: '[name].js',
    path: `${__dirname}/../dist`
  }
};

build_a.js

const merge = require('webpack-merge');
const webpack = require('webpack');
const base = require('./_base');
const path = require('path');

module.exports = merge(base, {
  dependencies: ['common'],
  entry: {
    'a': ['./common', './a'],
  },
  plugins: [
    new webpack.DllReferencePlugin({
      manifest: path.resolve(base.output.path, 'common.manifest.json'),
    }),
  ],
});

build_common.js

const merge = require('webpack-merge');
const webpack = require('webpack');
const base = require('./_base');
const path = require('path');

module.exports = merge(base, {
  name: 'common',
  entry: ['./common'],
  output: {
    filename: 'common.js',
  },
  plugins: [
    new webpack.DllPlugin({
      path: path.resolve(base.output.path, 'common.manifest.json'),
    }),
  ],
});

js_a.js

console.log('a');

js_common.js

__webpack_public_path__ = "https://cdn.example.com/x3ad76/js"

webpack.config.js

const base = require('./build/_base');
const common = require('./build/common');
const a = require('./build/a');

module.exports = [
  // common,
  a,
];

Note: put the build_ prefixed files in the /build folder and js_ prefixed ones in the js folder. npm install webpack webpack-merge and ./node_modules/.bin/webpack --verbose. You'll get: Cannot read property 'hash' of null as the only output in webpack 3.5.5.