Plugin Error: "Unable to find component class"
So what happened was I un-gitignored my Composer files so I could deploy them to another environment. Then I switched from that branch to a different branch with different Composer files. After I switched back, I ran into a Composer bug (mentioned here in the docs) where Composer will forget about plugins loaded using the path method if the files change.

So I had to perform these steps:


navigate to my craft project folder in the terminal
execute composer remove kgrote/siteutilities
delete the kgrote directory from craft/vendor
execute composer install kgrote/siteutilities


SUUUUUPER annoying, but there you have it.