issue after trying to avoid screen blanking
Say your screen is going dark after the period of time you have set in the settings. You can see this happening because the screen darkens gradually.
Say, you are just at your desk and want to stop that, because you don't want to relogin and retype your password. Then, if you move your mouse, you might be able or not to stop the darkening process of the screen. But if you do it too late, the screen blankens completely and you have to type your password to unlock your session.
The problem is when this is happening (meaning moving mouse while screen darken but screen lock nonetheless), then you end up with a broken gnome-shell session. The top bar has disappeared. And all extensions are disabled.
Using gnome-shell 3.30.1-2ubuntu1.18.10.2 on ubuntu 18.10 using wayland