Minecraft Run Not Finding Mod (SOLVED)

Hello, I have encountered a serious problem. 

When I run my mod in the workspace, it says "MOD LOADING ERROR" during loading and then says that my main folder (-my mod folder-/src/main) "has mods that were not found".

I tried deleting the last elements I added, nothing special, just an entity and a couple items, but then he said that some mod elements didn't compile properly.

Before this, it said that he couldn't send event for any of the minecraft vanilla elements. Now it can't find symbol for all of my mod's entities.

Edit: turns out that this is what happens when you define a mob in another one's AI targets and then delete the mob. I hope this helps someone.