Resolve modules which have been added using `npm link` or `yarn link`

webpack.config.js

const fs = require('fs')
const path = require('path')

// absolute paths to all symlinked modules inside `nodeModulesPath`
// adapted from https://github.com/webpack/webpack/issues/811#issuecomment-405199263
const findLinkedModules = (nodeModulesPath) => {
  const modules = []

  fs.readdirSync(nodeModulesPath).forEach(dirname => {
    const modulePath = path.resolve(nodeModulesPath, dirname)
    const stat = fs.lstatSync(modulePath)

    if (dirname.startsWith('.')) {
      // not a module or scope, ignore
    } else if (dirname.startsWith('@')) {
      // scoped modules
      modules.push(...findLinkedModules(modulePath))
    } else if (stat.isSymbolicLink()) {
      const realPath = fs.realpathSync(modulePath)
      const realModulePath = path.resolve(realPath, 'node_modules')

      modules.push(realModulePath)
    }
  })

  return modules
}

module.exports = {
  resolve: {
    // work with npm link
    // see https://github.com/webpack/webpack/issues/985
    // see https://github.com/vuejs-templates/webpack/pull/688
    symlinks: false,
    modules: [
      // provide absolute path to the main node_modules,
      // to avoid webpack searching around and getting confused
      // see https://webpack.js.org/configuration/resolve/#resolve-modules
      path.resolve('node_modules'),
      // include linked node_modules as fallback, in case the deps haven't
      // yet propagated to the main node_modules
      ...findLinkedModules(path.resolve('node_modules')),
    ],
  },
}