Some Misc Bugfixes (#22225)

This PR fixes a few bugs that were recently reported both by players and
by our new bug monitoring system. An AI agent (specifically Gemini 3)
was used to do some of the code diving process, while the fixes were
tested and verified myself manually. Yes I have actually verified the
fixes in this PR in testing.

The swap to Calculus methods for organ EMP was done by me, no AI. I love
Calculus to much to let a bot do it for me. In particular my fix to
organ EMP was to make it so that EMP damage is handled directly as
"number of fractional seconds the EMP will last", and that they tick
down cleanly per second. I did this because after fixing mechanical
organs not doing ANY EMP effects at all, I tested them and discovered
that the EMP effects were extremely underwhelming. They were like, "Your
screen only briefly filling with static for like 2 ticks", and "your
heart skips a single beat", which was lame and nonthreatening.
Significantly more fun is making the static last for N number of
seconds, and for the Heart to fail to pump for N number of seconds (very
life threatening!)

The new organ EMP handling vars are per-organ rather than a define, so
if we want there to be different EMP times for hearts vs eyes, that's
totally doable. Just make the heart have a larger recovery rate, or the
eyes have a smaller recovery rate.

---------

Signed-off-by: VMSolidus <evilexecutive@gmail.com>
Co-authored-by: Arrow768 <1331699+Arrow768@users.noreply.github.com>

code/modules/organs/internal/appendix.dm

@@ -65,8 +65,9 @@
 			owner.Weaken(10)
 
 		var/obj/item/organ/external/E = owner.get_organ(parent_organ)
-		E.sever_artery()
-		E.germ_level = max(INFECTION_LEVEL_TWO, E.germ_level)
+		if(E)
+			E.sever_artery()
+			E.germ_level = max(INFECTION_LEVEL_TWO, E.germ_level)
 		owner.adjustToxLoss(25)
 		removed()
 		qdel(src)

code/modules/organs/organ.dm

@@ -17,8 +17,14 @@
 
 	//Organ damage stats.
 	var/damage = 0 // amount of damage to the organ
-	var/surge_damage = 0 // EMP damage counter.
-	var/surge_time   = 0
+	/// Total amount of EMP damage a mechanical organ has taken. Effectively equal to "number of seconds the organ EMP effect will last".
+	var/surge_damage = 0.0
+	/**
+	 * The amount of EMP damage a mechanical organ will recover per second.
+	 * Fractional and floating points are allowed, but it shouldn't ever be negative.
+	 */
+	var/surge_recovery_per_second = 1.0
+
 	var/min_broken_damage = 30
 	var/min_bruised_damage = 10 // Damage before considered bruised
 	var/max_damage = 30
@@ -65,7 +71,7 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 			LOG_DEBUG("[src] at [loc] spawned without a proper DNA.")
 		var/mob/living/carbon/human/H = holder
 		if(istype(H))
-			if(internal)
+			if(internal && parent_organ)
 				var/obj/item/organ/external/E = H.get_organ(parent_organ)
 				if(E)
 					if(E.internal_organs == null)
@@ -158,52 +164,52 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 	if(istype(loc,/obj/structure/closet/body_bag/cryobag) || istype(loc,/obj/structure/closet/crate/freezer) || istype(loc,/obj/item/storage/box/unique/freezer))
 		return
 	//Process infections
-	if ((status & ORGAN_ROBOT) || (owner && owner.species && (owner.species.flags & IS_PLANT)))
+	var/is_immune = ((status & ORGAN_ROBOT) || robotic >= ROBOTIC_MECHANICAL || (owner && owner.species && (owner.species.flags & IS_PLANT)))
+	if (is_immune)
 		germ_level = 0
-		return
 
-	if(BP_IS_ROBOTIC(src) && surge_damage)
-		tick_surge_damage()
+	if((BP_IS_ROBOTIC(src) || robotic >= ROBOTIC_MECHANICAL) && surge_damage)
+		tick_surge_damage(seconds_per_tick)
 
 	if(!owner)
 		if (QDELETED(reagents))
 			LOG_DEBUG("Organ [DEBUG_REF(src)] had QDELETED reagents! Regenerating.")
 			create_reagents(5)
 
-		if(REAGENT_VOLUME(reagents, /singleton/reagent/blood) && !(status & ORGAN_ROBOT) && prob(40))
+		if(REAGENT_VOLUME(reagents, /singleton/reagent/blood) && !is_immune && prob(40))
 			reagents.remove_reagent(/singleton/reagent/blood,0.1)
 			if (isturf(loc))
 				blood_splatter(src,src,TRUE)
 		if(GLOB.config.organs_decay) damage += rand(1,3)
 		if(damage >= max_damage)
 			damage = max_damage
-		germ_level += rand(2,6)
-		if(germ_level >= INFECTION_LEVEL_TWO)
+		if(!is_immune)
 			germ_level += rand(2,6)
-		if(germ_level >= INFECTION_LEVEL_THREE)
-			die()
+			if(germ_level >= INFECTION_LEVEL_TWO)
+				germ_level += rand(2,6)
+			if(germ_level >= INFECTION_LEVEL_THREE)
+				die()
 
 
 	else if(owner.bodytemperature >= 170)	//cryo stops germs from moving and doing their bad stuffs
 		//** Handle antibiotics and curing infections
 		handle_antibiotics()
-		handle_immunosuppressants()
-		handle_rejection()
-		handle_germ_effects()
+		if(!is_immune)
+			handle_immunosuppressants()
+			handle_rejection()
+			handle_germ_effects()
 
 	//check if we've hit max_damage
 	if(damage >= max_damage)
 		die()
 
-/obj/item/organ/proc/tick_surge_damage()
-	if(surge_damage)
-		do_surge_effects()
-	if(surge_time + 1 SECOND < world.time)
-		surge_damage = max(0, surge_damage - 10)
-		surge_time = world.time
-		if(!surge_damage)
-			surge_time = 0
-			clear_surge_effects()
+/obj/item/organ/proc/tick_surge_damage(seconds_per_tick)
+	if(!surge_damage)
+		clear_surge_effects()
+		return
+
+	do_surge_effects()
+	surge_damage = max(0, surge_damage - (surge_recovery_per_second * seconds_per_tick))
 
 /obj/item/organ/proc/do_surge_effects()
 	return
@@ -232,10 +238,10 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 		if(antibiotics < 5 && prob(round(germ_level/7)))
 			germ_level++
 
-	if (germ_level >= INFECTION_LEVEL_TWO)
+	if (germ_level >= INFECTION_LEVEL_TWO && parent_organ)
 		var/obj/item/organ/external/parent = owner.get_organ(parent_organ)
 		//spread germs
-		if (antibiotics < 5 && parent.germ_level < germ_level && ( parent.germ_level < INFECTION_LEVEL_ONE*2 || prob(30) ))
+		if (parent && antibiotics < 5 && parent.germ_level < germ_level && ( parent.germ_level < INFECTION_LEVEL_ONE*2 || prob(30) ))
 			parent.germ_level++
 
 		if (prob(3))	//about once every 30 seconds
@@ -423,7 +429,6 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 		return //We check earlier, but just to make sure.
 
 	surge_damage = clamp(0, surge + surge_damage, MAXIMUM_SURGE_DAMAGE) //We want X seconds at most of hampered movement or what have you.
-	surge_time = world.time
 
 /**
  *  Remove an organ
@@ -443,7 +448,7 @@ INITIALIZE_IMMEDIATE(/obj/item/organ)
 	owner.internal_organs_by_name -= null
 	owner.internal_organs -= src
 
-	if(detach)
+	if(detach && parent_organ)
 		var/obj/item/organ/external/affected = owner.get_organ(parent_organ)
 		if(affected)
 			affected.internal_organs -= src

code/modules/organs/pain.dm

@@ -86,8 +86,9 @@
 
 	// Damage to internal organs hurts a lot.
 	for(var/obj/item/organ/internal/I in internal_organs)
-		if(prob(1) && !((I.status & ORGAN_DEAD) || BP_IS_ROBOTIC(I)) && I.damage > 5)
+		if(prob(1) && !((I.status & ORGAN_DEAD) || BP_IS_ROBOTIC(I)) && I.damage > 5 && I.parent_organ)
 			var/obj/item/organ/external/parent = get_organ(I.parent_organ)
+			if (!parent) continue
 			var/pain = 10
 			var/message = I.unknown_pain_location ? "You feel a dull pain in your [parent.name]..." : "You feel a dull pain radiating from your [I.name]..."
 			if(I.is_bruised())