Slime core mob selection fix (#19289)

Marked some mobs that were not meant to be spawned as abstracts.
Updated the reaction of the slime core to not spawn abstract mobs.

Fixes #19276

code/modules/mob/living/simple_animal/aquatic.dm

@@ -1,5 +1,7 @@
 //For things that swim and don't do much else.
 /mob/living/simple_animal/aquatic
+	abstract_type = /mob/living/simple_animal/aquatic
+
 	name = "aquatic animal"
 	desc = DESC_PARENT
 	icon = 'icons/mob/npc/fish.dmi'

code/modules/mob/living/simple_animal/hostile/commanded/commanded.dm

@@ -1,4 +1,6 @@
 /mob/living/simple_animal/hostile/commanded
+	abstract_type = /mob/living/simple_animal/hostile/commanded
+
 	name = "commanded"
 	var/short_name = null
 	stance = COMMANDED_STOP

code/modules/mob/living/simple_animal/hostile/hostile.dm

@@ -1,4 +1,6 @@
 /mob/living/simple_animal/hostile
+	abstract_type = /mob/living/simple_animal/hostile
+
 	faction = "hostile"
 	var/stance = HOSTILE_STANCE_IDLE	//Used to determine behavior
 	var/mob/living/target_mob

code/modules/mob/living/simple_animal/hostile/retaliate/aquatic.dm

@@ -1,5 +1,7 @@
 //For things that swim and don't do much else, but also bite!
 /mob/living/simple_animal/hostile/retaliate/aquatic
+	abstract_type = /mob/living/simple_animal/hostile/retaliate/aquatic
+
 	name = "aquatic animal"
 	desc = DESC_PARENT
 	icon = 'icons/mob/npc/fish.dmi'

code/modules/mob/living/simple_animal/hostile/retaliate/retaliate.dm

@@ -1,4 +1,6 @@
 /mob/living/simple_animal/hostile/retaliate
+	abstract_type = /mob/living/simple_animal/hostile/retaliate
+
 	var/list/enemies = list()
 
 /mob/living/simple_animal/hostile/retaliate/Destroy()

code/modules/reagents/Chemistry-Recipes.dm

@@ -1243,6 +1243,7 @@
 	required = /obj/item/slime_extract/gold
 
 /datum/chemical_reaction/slime/crit/on_reaction(var/datum/reagents/holder)
+	//exclusion list for things you don't want the reaction to create
 	var/blocked = list(
 		/mob/living/simple_animal/hostile,
 		/mob/living/simple_animal/hostile/pirate,
@@ -1255,10 +1256,8 @@
 		/mob/living/simple_animal/hostile/syndicate/ranged,
 		/mob/living/simple_animal/hostile/syndicate/ranged/space,
 		/mob/living/simple_animal/hostile/faithless,
-		/mob/living/simple_animal/hostile/retaliate,
 		/mob/living/simple_animal/hostile/retaliate/clown,
 		/mob/living/simple_animal/hostile/true_changeling,
-		/mob/living/simple_animal/hostile/commanded,
 		/mob/living/simple_animal/hostile/commanded/dog,
 		/mob/living/simple_animal/hostile/commanded/dog/amaskan,
 		/mob/living/simple_animal/hostile/commanded/dog/columbo,
@@ -1281,7 +1280,7 @@
 		/mob/living/simple_animal/hostile/cavern_geist/augmented,
 		/mob/living/simple_animal/hostile/retaliate/pra_exploration_drone
 	)
-	//exclusion list for things you don't want the reaction to create.
+
 	var/list/critters = typesof(/mob/living/simple_animal/hostile) - blocked // list of possible hostile mobs
 	var/turf/location = get_turf(holder.my_atom)
 	playsound(location, 'sound/effects/phasein.ogg', 100, 1)
@@ -1290,6 +1289,15 @@
 
 	for(var/i = 1, i <= 5, i++)
 		var/chosen = pick(critters)
+		//No abstract mobs
+		while(is_abstract(chosen))
+			critters -= chosen
+			if(!length(critters))
+				crash_with("No critters left to pick from!")
+				return
+
+			chosen = pick(critters)
+
 		var/mob/living/simple_animal/hostile/C = new chosen
 		C.faction = "slimesummon"
 		C.forceMove(location)