Cannot read property 'appendChild' of undefined at mtc.js:1

Anyone has been getting this in the browser console for some time now? This is an external page with Mautic script included. It worked flawlessly before.

Code:
Cannot read property 'appendChild' of undefined at mtc.js:1

Best,
D.

Anyone has been getting this in the browser console for some time now? This is an external page with Mautic script included. It worked flawlessly before.

Cannot read property 'appendChild' of undefined at mtc.js:1

Best,
D.