you'd think by now people would understand version control. a whole days work gone because of bad merging.

Just before I left my last place, someone managed to merge all the untested & unaccepted work into the current release. 2 days before it was deployed!

Version control is not hard, if someone can't do it, can they be trusted to write code?

Sad. That should not happen. Maybe need some procedures and accountability if they are not followed. Too bad you could not roll-back to the prior state. Good luck.

I used to use git strictly on the CLI, but I know use the VCS GUI on my IDE and it has really helped me and my coworker to avoid any issues since it's harder to mess up.

I use smartgit as a GUI. Really like it. also had a co-worker once merged staging into master by accident. it was several commits and feature releases later that it was discovered. had to spend a day or 2 on that too!