Yes, any request can get stuck at any time.

That is what's happening any time you've seen a website that randomly decides to load without styles, or with a missing image.

The good thing is that it's very apparent when that happens and you can just reload the page.

But it's not immediately obvious when it happens with a JS file.

That's half the reason why you shouldn't re-implement css features in a js file. (the other half is performance)