code: function createHtmlDocument (message) {
    var body = escapeHtml(message)
      .replace(NEWLINE_REGEXP, '<br>')
      .replace(DOUBLE_SPACE_REGEXP, ' &nbsp;')
  
    return '<!DOCTYPE html>\n' +
      '<html lang="en">\n' +
      '<head>\n' +
      '<meta charset="utf-8">\n' +
      '<title>Error</title>\n' +
      '</head>\n' +
      '<body>\n' +
      '<pre>' + body + '</pre>\n' +
      '</body>\n' +
      '</html>\n'
  }
docs: Create a minimal HTML document.
  
  @param {string} message
  @private