I need help with being able to have more than one enemy in the game.

I followed Brakeys RPG Tutorial and I tried adding two enemies in the game after finishing the series but when I attack the second enemy, the player attacks the other enemies health and when the other enemy dies and I keep attacking the second enemy, I get... MissingReferenceException: The object of type 'EnemyStats' has been destroyed but you are still trying to access it. Your script should either check if it is null or you should not destroy the object. it then references me to the CharacterCombat script and the CharacterStats script. thank you for any help.