Object reference not set to an instance of an object.

I've been trying to set up a 3D melee attack script based on one of Brackey's videos and I keep getting the same error when I interact with the object, instead of it taking damage, I get this error. I have checked hundreds of times and im pretty sure I have referenced eveything. Plz help...
(the error is in line 25 in the meleeCombat script)