Improve nearsighted code (#66327)

This refactors the nearsighted code into it's own proc that was salvaged from #66306. Just a code improvement with no game changes.

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

@@ -766,6 +766,12 @@
 	heat_exposure_stacks = 0
 	return ..()
 
+/mob/living/carbon/human/is_nearsighted()
+	var/obj/item/clothing/glasses/eyewear = glasses
+	if(istype(eyewear) && eyewear.vision_correction)
+		return FALSE
+	return ..()
+
 /mob/living/carbon/human/is_literate()
 	return TRUE
 

code/modules/mob/living/living_fov.dm

@@ -45,14 +45,7 @@
 		. = TRUE
 
 	// Handling nearsightnedness
-	if(. && HAS_TRAIT(src, TRAIT_NEARSIGHT))
-		//Checking if our dude really is suffering from nearsightness! (very nice nearsightness code)
-		if(iscarbon(src))
-			var/mob/living/carbon/carbon_me = src
-			if(carbon_me.glasses)
-				var/obj/item/clothing/glasses/glass = carbon_me.glasses
-				if(glass.vision_correction)
-					return
+	if(. && is_nearsighted())					
 		if((rel_x >= NEARSIGHTNESS_FOV_BLINDNESS || rel_x <= -NEARSIGHTNESS_FOV_BLINDNESS) || (rel_y >= NEARSIGHTNESS_FOV_BLINDNESS || rel_y <= -NEARSIGHTNESS_FOV_BLINDNESS))
 			return FALSE
 

code/modules/mob/mob.dm

@@ -1144,6 +1144,10 @@
 /mob/proc/has_nightvision()
 	return see_in_dark >= NIGHTVISION_FOV_RANGE
 
+/// Is this mob affected by nearsight
+/mob/proc/is_nearsighted()
+	return HAS_TRAIT(src, TRAIT_NEARSIGHT)
+
 /// This mob is abile to read books
 /mob/proc/is_literate()
 	return FALSE