code: function makeFilenameRegex(name) {
    if (!_.isString(name)) {
      throw new TypeError('name parameter must be of type "String"');
    }
  
    const regexString = `^${name}(?:[.](.+))?.(${fileExtensions.join('|')})$`;
    return new RegExp(regexString);
  }
docs: make new RegExp object to match file names that fit the pattern <name>[.env].ext
  @param  {String}           name        base name of the file
  @return {RegExp}                       RegExp generated from base name and extensions