[NPCs] Game crashes when "sleeping" npc_helicopter is killed

[somehundred]

Describe the bug

If npc_helicopter is inactive and waiting for Activate input and it's health is depleted in some way (SelfDestruct input, SetHealth 0 input), game crashes. This is Half-Life 2 bug.

Steps to reproduce

Steps to reproduce the behavior:

1. Load a map where helicopter spawns asleep. Let's use d1_canals_01 for example.
2. Don't go anywhere. Deplete helicopter's health with ent_fire npc_helicopter selfdestruct.
3. Game crashes

Expected behavior

Game does not crash.