Ports more missing limb checks from polaris and fixes removing hands not dropping items. (#4212)

-adds more checks for missing limbs in the icon updates
-fixes #4140

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

@@ -169,7 +169,7 @@ There are several things that need to be remembered:
 	var/damage_appearance = ""
 
 	for(var/obj/item/organ/external/O in organs)
-		if(O.is_stump())
+		if(isnull(O) || O.is_stump())
 			continue
 		//if(O.status & ORGAN_DESTROYED) damage_appearance += "d" //what is this?
 		//else
@@ -187,7 +187,7 @@ There are several things that need to be remembered:
 
 	// blend the individual damage states with our icons
 	for(var/obj/item/organ/external/O in organs)
-		if(O.is_stump())
+		if(isnull(O) || O.is_stump())
 			continue
 
 		O.update_icon()

code/modules/organs/subtypes/standard.dm

@@ -125,6 +125,10 @@
 
 /obj/item/organ/external/hand/removed()
 	owner.drop_from_inventory(owner.gloves)
+	if(body_part == HAND_LEFT)
+		owner.drop_l_hand()
+	else
+		owner.drop_r_hand()
 	..()
 
 /obj/item/organ/external/hand/right

html/changelogs/alberyk-nohand.yml

@@ -0,0 +1,6 @@
+author: Alberyk
+
+delete-after: True
+
+changes: 
+  - bugfix: "Cutting someone's hand should now force them to drop the item they are holding on said hand."