constructor(config) {
    const {
      nodeModulesPath,
      packageJsonPath,
    } = config;

    // Ensure required params are set
    if ([
      nodeModulesPath,
      packageJsonPath,
    ].includes(undefined)) {
      throw 'invalid configuration';
    }

    this.nodeModulesPath = nodeModulesPath;
    this.packageJsonPath = packageJsonPath;
  }
The constructor.
@param {Object} config The config.
@param {String} config.nodeModulesPath The path to the node_modules directory.
@param {String} config.packageJsonPath The path to the parent package.json file.