Custom Entity makes a compiling error

So i was working on a project where i would add a turret mob that would shoot at the player. when i was done making the mob and tested it it works fine.But i wanted to make it rapid fire. So followed some instructions on google to mess around with the code. Then  a pop up showed up saying "Your workspace has mod elements that dont compile properly" and it was caused by the mob. And the i deleted the mob and made it again (this time without messing with the code) and now its doesn't work anymore. sorry if this problem was posted before or the wrong category.