The HTML of the OSM.org changed again. For anyone looking for a fix you can change lines 12-23 to this:

var primary = document.getElementById('edit_tab');
if (!primary) {
    return;
}

var displayContainer = document.createElement('div');
var buttonGroup = document.createElement('div');
buttonGroup.setAttribute('class', 'btn-group');

var overpassDisplayContainer = document.createElement('div');
var overpassButtonGroup = document.createElement('div');
overpassButtonGroup.setAttribute('class', 'btn-group');

@DavidKarlas Thank you so much!

Hi!
This script is amazing. I am not exaggerating when I say that I use it everyday. It saves me so much element-ID-copying-pain :)

May I request a Button for the level0-Editor when viewing a way/node/relation?

function updateThings() {  
...
addButton("level0", "https://level0.osmz.ru/?url="+ type + id);
...
}