Runtime error when checking for Actor has tag

[florian_17.20 (LosPika)]

Hello,
my enemy character damaged themselves so I added the “Actor has tag”.
damageStateEnemy (Anim Notify State)

Now its working perfectly fine, the enemys arent damaging themselves, only me.
But now I get this error:

Whats the problem here?

[ClockworkOcean]

You have to check if ANYTHING was hit