Don't re-damage object with arrow if already dead

mods/ITEMS/mcl_bows/arrow.lua

@@ -184,26 +184,28 @@ ARROW_ENTITY.on_step = function(self, dtime)
 			local is_player = obj:is_player()
 			local lua = obj:get_luaentity()
 			if obj ~= self._shooter and (is_player or (lua and lua._cmi_is_mob)) then
-				obj:punch(self.object, 1.0, {
-					full_punch_interval=1.0,
-					damage_groups={fleshy=self._damage},
-				}, nil)
+				if obj:get_hp() > 0 then
+					obj:punch(self.object, 1.0, {
+						full_punch_interval=1.0,
+						damage_groups={fleshy=self._damage},
+					}, nil)
 
-				if is_player then
-					if self._shooter and self._shooter:is_player() then
-						-- “Ding” sound for hitting another player
-						minetest.sound_play({name="mcl_bows_hit_player", gain=0.1}, {to_player=self._shooter})
+					if is_player then
+						if self._shooter and self._shooter:is_player() then
+							-- “Ding” sound for hitting another player
+							minetest.sound_play({name="mcl_bows_hit_player", gain=0.1}, {to_player=self._shooter})
+						end
 					end
-				end
 
-				if lua then
-					local entity_name = lua.name
-					-- Achievement for hitting skeleton, wither skeleton or stray (TODO) with an arrow at least 50 meters away
-					-- NOTE: Range has been reduced because mobs unload much earlier than that ... >_>
-					-- TODO: This achievement should be given for the kill, not just a hit
-					if self._shooter and self._shooter:is_player() and vector.distance(pos, self._startpos) >= 20 then
-						if mod_awards and (entity_name == "mobs_mc:skeleton" or entity_name == "mobs_mc:stray" or entity_name == "mobs_mc:witherskeleton") then
-							awards.unlock(self._shooter:get_player_name(), "mcl:snipeSkeleton")
+					if lua then
+						local entity_name = lua.name
+						-- Achievement for hitting skeleton, wither skeleton or stray (TODO) with an arrow at least 50 meters away
+						-- NOTE: Range has been reduced because mobs unload much earlier than that ... >_>
+						-- TODO: This achievement should be given for the kill, not just a hit
+						if self._shooter and self._shooter:is_player() and vector.distance(pos, self._startpos) >= 20 then
+							if mod_awards and (entity_name == "mobs_mc:skeleton" or entity_name == "mobs_mc:stray" or entity_name == "mobs_mc:witherskeleton") then
+								awards.unlock(self._shooter:get_player_name(), "mcl:snipeSkeleton")
+							end
 						end
 					end
 				end