sanitize-html bug

index.js

const sanitizeHtml = require('sanitize-html');

const ALLOWED_SCHEMES = ['data', 'http', 'https', 'mailto'];

const text = 'Below\n' +
'<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAABHNCSVQICAgIfAhkiAAAAMFJREFUOE+lU9sRg0AIZDNpym9rSAumJm0hNfidsgic5w1wGJ1kZ3zgwvI4AQtIAHrq4zKY5uJ715sGP7C44BdPnZj1gaRVERBPpYJfUSpoGLeyir2Glg64mxMQg9f6xQbU94zrBDBWgVCBBmecbyGWbcrLgpX+OkR+L4ShPw3bdtdCnMmZfSig2a+gtcD1R0LyA1mh6OdmsJNnmW0Sfwp75LYevQ5AsUI3g0aKI+llEe3KQbcx28SsnZi9LNO/6/wBmhVJ7HDmOd4AAAAASUVORK5CYII=" alt="image.png" />\n' +
'Above';

const sanitized = sanitizeHtml(text, {
    allowedTags: ['img', 'span'],
    allowedAttributes: { img: ['src'] },
    allowedSchemes: ALLOWED_SCHEMES,
    transformTags: {
      'img': (_tagName, attribs) => {
        return {
            tagName: 'span',
            attribs: {},
            text: `[image: ${attribs.alt || attribs.title || 'no name'}]`
        };
      },
    }
  });

console.log("sanitized:\n" + sanitized);

package.json

{
  "name": "sanitize-html-test",
  "version": "1.0.0",
  "description": "Sample project for https://github.com/apostrophecms/sanitize-html/issues/506",
  "dependencies": {
    "sanitize-html": "2.5.2"
  },
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Flowcrypt a.s.",
  "license": "MIT"
}