如何使其仅在使用async await生成pdf之后才发送pdf

const PDFDocument = require('pdfkit');
const fs = require('fs');
const nodemailer = require('nodemailer');

async function generateAndSendPDF() {
  // 生成PDF
  const doc = new PDFDocument();
  doc.text('Hello, World!');
  const pdfPath = 'path/to/generated.pdf';
  doc.pipe(fs.createWriteStream(pdfPath));
  doc.end();

  // 发送PDF
  const transporter = nodemailer.createTransport({
    // 配置邮件传输
  });

  const mailOptions = {
    from: 'sender@example.com',
    to: 'recipient@example.com',
    subject: 'PDF Attachment',
    text: 'Please find the attached PDF file.',
    attachments: [
      {
        filename: 'generated.pdf',
        path: pdfPath
      }
    ]
  };

  await transporter.sendMail(mailOptions);
  console.log('PDF sent successfully!');
}

generateAndSendPDF().catch(error => {
  console.error('Error generating and sending PDF:', error);
});