Drupal website - Add "defer" to script instructions

[esaumell]

While setting up the banner on our Drupal website we had to add defer like this
<script defer src="https://keepandroidopen.org/banner.js?lang=ca&size=mini&id=keepandroidopen"></script>
while adding it to the section of html.html.twig template to make it work.

[marcprux]

Interesting. Do you happen to know why defer was needed? Did is simply not work without it, or was there some error in the JavaScript console?

[esaumell]

Uncaught TypeError: Cannot read properties of null (reading 'insertBefore')