Error compiling with no known errors

The IDE adds:

void main(void) {
  sei();
  init();
  setup();
  for(;;){
    loop();
  }
}

Or something like that.

If you don't want loop() or setup(), just use this in your code instead:

void main(void) {
  sei();
  init();
  
  //Your code here
  
  exit();
}