Fix observe runtime (#30437)

* fix

* keep update_sight()

code/modules/mob/dead/observer/observer_base.dm

@@ -866,7 +866,7 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 	mob_observed = null
 	reset_perspective(null)
 	client?.perspective = initial(client.perspective)
-	set_sight(initial(sight))
+	update_sight()
 	UnregisterSignal(src, COMSIG_ATOM_ORBITER_STOP)
 
 	if(s_active)

code/modules/mob/living/carbon/human/species/_species.dm

@@ -1045,13 +1045,6 @@ It'll return null if the organ doesn't correspond, so include null checks when u
 			if(!isnull(hat.lighting_alpha))
 				H.lighting_alpha = min(hat.lighting_alpha, H.lighting_alpha)
 
-	if(H.vision_type)
-		H.sight |= H.vision_type.sight_flags
-		H.see_in_dark = max(H.see_in_dark, H.vision_type.see_in_dark)
-
-		if(!isnull(H.vision_type.lighting_alpha))
-			H.lighting_alpha = min(H.vision_type.lighting_alpha, H.lighting_alpha)
-
 	if(HAS_TRAIT(H, TRAIT_MESON_VISION))
 		H.sight |= SEE_TURFS
 		H.lighting_alpha = min(H.lighting_alpha, LIGHTING_PLANE_ALPHA_MOSTLY_VISIBLE)

code/modules/mob/mob.dm

@@ -1353,12 +1353,6 @@ GLOBAL_LIST_INIT(slot_equipment_priority, list( \
 	SEND_SIGNAL(src, COMSIG_MOB_UPDATE_SIGHT)
 	sync_lighting_plane_alpha()
 
-/mob/proc/set_sight(datum/vision_override/O)
-	QDEL_NULL(vision_type)
-	if(O) //in case of null
-		vision_type = new O
-	update_sight()
-
 /mob/proc/sync_lighting_plane_alpha()
 	if(hud_used)
 		var/atom/movable/screen/plane_master/lighting/L = hud_used.plane_masters["[LIGHTING_PLANE]"]

code/modules/mob/mob_vars.dm

@@ -183,8 +183,6 @@
 
 	var/resize = 1 //Badminnery resize
 
-	var/datum/vision_override/vision_type = null //Vision override datum.
-
 	var/list/permanent_huds = list()
 
 	var/list/actions = list()