I have a simple Angular app, that is a collection of small example apps.
(The code can be found on GitHub, and the homepage is here.)

I work on it locally.
Suddenly the following error message is all over my console, when I do ng serve:

Watchpack Error (watcher): Error: ENOSPC:
System limit for number of file watchers reached,
watch ‘/home/tilman/Code/angular_examples/node_modules/blah/blah’

But the app still works. There seems to be no problem, except my flooded console.

Some details:
   Ubuntu 20.04
   PyCharm 2024.1.3 (Professional Edition)
   Angular CLI: 13.3.4
   Node: 17.9.0 (Unsupported, according to ng v)
   Package Manager: npm 8.5.5
   /proc/sys/fs/inotify/max_user_watches: 65536

Similar questions have been asked about React in 2019 and about Angular in 2021.
The answers sound like: Pressing some buttons worked for me.
But I would like to know what is going on here.

I was not aware, that file watchers are a thing.
Do I need them? Where are they? Why are there so many? How to clean them up?

One of the proposed solutions is deleting and reinstalling node_modules.
That is not a good way to solve problems. (What if something is gone, when I try to reinstall it?)

Here is a screenshot, showing Compiled successfully among the error messages: