document.body.insertBefore on iOs Safari not working

I'm creating an embedding system, however I'm having problems with safari on iOs, I call the html of my code through an ajax request, but Safari on iOs was the only browser that did not embed the code.

Code used to insert element into the page:

var el = document.createElement('div');
el.setAttribute('id', 'chat-robbu');
el.setAttribute('style', 'display: none;');
el.innerHTML = data.html; // data.html is I received through an object through an ajax
document.body.insertBefore(el, document.body.children[0]);

You can see the code working here: https://chatrobbu.rilo.com.br

from document.body.insertBefore on iOs Safari not working