Script to modify HP crashes Zquest?

In one room, I have the player direct warp to a boss room. In that room, there is a Ghoma and an FFC running this script. The player hits the warp, the boss music (set on the boss screen) starts to play, but then the screen goes black (before the Ghoma or his screen is visible) and the game crashes.

// ======================================================
// BOSS_BOOSTER = This FFC increases the hit points of the
// first NPC so it can be used as a boss.
// D0 = New hit points.
// =====================================================
ffc script boss_booster{
	void run(int hitpoint_boost)
		npc current_enemy = Screen->LoadNPC(1);
		current_enemy->HP = hitpoint_boost;
	
	} // end of void run
} // end of script

Any ideas?