Uncaught (in promise) TypeError: Cannot set properties of null (setting 'innerText')

Question

I'm trying to display the content from /terminal/input.txt in the div output.

HTML body:

<div className="events">
  <Navbar />
  <p id="output"></p>
  <Footer />
</div>

Javascript:

var output = document.getElementById('output');
var out;
fetch("/terminal/input.txt")
  .then(res => res.text())
  .then(data => {
    out = data;
  }).then(() => {
    output.innerText = out;
  });

ERROR: Uncaught (in promise) TypeError: Cannot set properties of null (setting 'innerText')

Can you please help me thanks in advance