I just tried publishing a library to to Community, and got an incomprehensible red snackbar saying “could not publish file… status 403”.

I looked into the dev console, there was nothing useful there. Thankfully I knew I could go to the Network tab, find the failed request and look at the response:

And only after that I was able to understand what exactly was wrong and what I needed to do. This is not user-friendly at all. If there’s a perfectly fine error message in the network response, it should be shown to the user in the UI.