My finder's sidebar is empty My finder's sidebar is empty (see attachement), this happens about once every two weeks, I would be working on my mac and suddenly the sidebar becomes empty.

It works again after a restart, but it is a great inconvenience to have to do that each time.
The first thing I would do is run a cleaning utility (like Onyx), reboot and see if cleaning up caches, running disk repair, maintenance scripts, etc. does the trick.

Failing that go to Apple support and download the latest Combo Updater that matches your current OS version and run that. Combo updaters often fix odd macOS behavior.