Fixes three borer runtimes and also a hookshot runtime. (#10608)

code/game/objects/items/weapons/swords_axes_etc.dm

@@ -258,8 +258,10 @@
 		return
 	if(!parent_borer.channeling_bone_sword) //the borer has stopped sustaining the sword
 		qdel(src)
+		return
 	if(parent_borer.chemicals < 5) //the parent borer no longer has the chemicals required to sustain the sword
 		qdel(src)
+		return
 	else
 		parent_borer.chemicals -= 5
 		sleep(10)

code/modules/mob/living/simple_animal/borer/fleshshot.dm

@@ -308,6 +308,7 @@
 				visible_message("With a tearing noise, the length of flesh mysteriously snaps and retracts back into its arm.")
 				hookshot.cancel_chain()
 				bullet_die()
+				return
 			HC.loc = loc
 			HC.pixel_x = pixel_x
 			HC.pixel_y = pixel_y

code/modules/organs/organ_external.dm

@@ -1284,6 +1284,7 @@ obj/item/weapon/organ/l_arm
 	part = "l_arm"
 obj/item/weapon/organ/l_arm/New(loc, mob/living/carbon/human/H)
 	..()
+	if(H && istype(H))
 		var/mob/living/simple_animal/borer/B = H.has_brain_worms("l_arm")
 		if(B)
 			B.infest_limb(src)
@@ -1304,6 +1305,7 @@ obj/item/weapon/organ/l_leg
 	part = "l_leg"
 obj/item/weapon/organ/l_leg/New(loc, mob/living/carbon/human/H)
 	..()
+	if(H && istype(H))
 		var/mob/living/simple_animal/borer/B = H.has_brain_worms("l_leg")
 		if(B)
 			B.infest_limb(src)
@@ -1314,6 +1316,7 @@ obj/item/weapon/organ/r_arm
 	part = "r_arm"
 obj/item/weapon/organ/r_arm/New(loc, mob/living/carbon/human/H)
 	..()
+	if(H && istype(H))
 		var/mob/living/simple_animal/borer/B = H.has_brain_worms("r_arm")
 		if(B)
 			B.infest_limb(src)
@@ -1334,6 +1337,7 @@ obj/item/weapon/organ/r_leg
 	part = "r_leg"
 obj/item/weapon/organ/r_leg/New(loc, mob/living/carbon/human/H)
 	..()
+	if(H && istype(H))
 		var/mob/living/simple_animal/borer/B = H.has_brain_worms("r_leg")
 		if(B)
 			B.infest_limb(src)
@@ -1392,6 +1396,7 @@ obj/item/weapon/organ/head/New(loc, mob/living/carbon/human/H)
 	if(brainmob && brainmob.client)
 		brainmob.client.screen.len = null //clear the hud
 
+	if(H && istype(H))
 		var/mob/living/simple_animal/borer/B = H.has_brain_worms()
 		if(B)
 			B.infest_limb(src)

code/modules/projectiles/projectile/hookshot.dm

@@ -40,6 +40,7 @@
 				visible_message("With a CLANG noise, the chain mysteriously snaps and rewinds back into the hookshot.")
 				hookshot.cancel_chain()
 				bullet_die()
+				return
 			HC.loc = loc
 			HC.pixel_x = pixel_x
 			HC.pixel_y = pixel_y