Cannot run client to test, wants me to enter safe mod

I wanted to add some files from another mod I saw in a video to the one I'm working on into my workspace. After loading up MCreator, the files didn't load because I placed them in the wrong folder I'm assuming, so I remove the files I added then loaded up MCreator to test it and I got this error. I believe theres a file (that I can't find) that still in the workspace or I accidently removed a file I wasn't supposed to. I also tried loading a earlier build from my backups but still didn't work.