args SUCK

code/modules/mob/living/living_defense.dm

@@ -620,7 +620,7 @@
   * If the method is INGEST the mob tastes the reagents.
   * If the method is VAPOR it incorporates permiability protection.
   */
-/mob/living/expose_reagents(list/reagents, datum/reagents/source, method=TOUCH, volume_modifier=1, show_message=TRUE)
+/mob/living/expose_reagents(list/reagents, datum/reagents/source, method=TOUCH, volume_modifier=1, show_message=TRUE, obj/item/bodypart/affecting)
 	if((. = ..()) & COMPONENT_NO_EXPOSE_REAGENTS)
 		return
 
@@ -630,4 +630,4 @@
 	var/touch_protection = (method == VAPOR) ? getarmor(null, BIO) * 0.01 : 0
 	for(var/reagent in reagents)
 		var/datum/reagent/R = reagent
-		. |= R.expose_mob(src, method, reagents[R], show_message, touch_protection)
+		. |= R.expose_mob(src, method, reagents[R], show_message, touch_protection, affecting)

code/modules/reagents/chemistry/holder.dm

@@ -680,12 +680,20 @@
 			can_process = TRUE
 	return can_process
 
+//================================Exposure(to apply reagent effects)======================
 /**
-  * Applies the relevant expose_ proc for every reagent in this holder
-  * * [/datum/reagent/proc/expose_mob]
-  * * [/datum/reagent/proc/expose_turf]
-  * * [/datum/reagent/proc/expose_obj]
-  */
+ * Applies the relevant expose_ proc for every reagent in this holder
+ * * [/datum/reagent/proc/expose_mob]
+ * * [/datum/reagent/proc/expose_turf]
+ * * [/datum/reagent/proc/expose_obj]
+ *
+ * Arguments
+ * - Atom/target: What mob/turf/object is being exposed to reagents? This is your reaction target.
+ * - Method: What reaction type is the reagent itself going to call on the reaction target? Types are TOUCH, INGEST, VAPOR, PATCH, and INJECT.
+ * - Volume_modifier: What is the reagent volume multiplied by when exposed? Note that this is called on the volume of EVERY reagent in the base body, so factor in your Maximum_Volume if necessary!
+ * - Show_message: Whether to display anything to mobs when they are exposed.
+ * -
+ */
 /datum/reagents/proc/expose(atom/A, method = TOUCH, volume_modifier = 1, show_message = 1, obj/item/bodypart/affecting)
 	if(isnull(A))
 		return null

code/modules/reagents/chemistry/reagents/medicine_reagents.dm

@@ -442,7 +442,7 @@
 			show_message = FALSE
 		if(method == PATCH)
 			//you could be targeting a limb that doesnt exist while applying the patch, so lets avoid a runtime
-			if(affecting?.heal_damage(brute = reac_volume, burn = reac_volume))
+			if(affecting.heal_damage(brute = reac_volume, burn = reac_volume))
 				M.update_damage_overlays()
 			M.adjustStaminaLoss(reac_volume*2)
 			if(show_message)