For question on https://www.facebook.com/groups/linebot/permalink/2774675056196396/

line_upload_to_imgur.js

function handleImage(message, replyToken) {
  axios.get(`https://api-data.line.me/v2/bot/message/${message.id}/content`, {
    headers: {
      'Authorization': `Bearer ${process.env.CHANNEL_ACCESS_TOKEN}`
    }, responseType: 'stream'
  }).then((res) => {
    const tmp = tempfile();
    const writer = fs.createWriteStream(tmp);
    res.data.pipe(writer);
    writer.on('finish', () => {
      imgur.setAccessToken(`${process.env.IMGUR_ACCESS_TOKEN}`);
      imgur
      .uploadFile(tmp)
      .then((json) => {
        return client.replyMessage(replyToken, {
          "type": "text",
          "text": `${JSON.stringify(json)}`
        });
      })
      .catch((err) => {
        console.error(err.message);
      });
    })
  });
}