Make the server not crash when players are killed by named mobs

mods/HUD/mcl_death_messages/init.lua

@@ -41,6 +41,9 @@ local msgs = {
 	["murder"] = {
 		N("@1 was slain by @2 using [@3]"),
 	},
+	["murder_by_named_mob"] = {
+		N("@1 was slain by @2."),
+	},
 	["murder_any"] = {
 		N("@1 was killed."),
 	},
@@ -212,7 +215,7 @@ minetest.register_on_dieplayer(function(player, reason)
 				end
 				hittersubtype = hitter:get_luaentity().name
 				if hittername then
-					msg = dmsg("murder", name, hittername)
+					msg = dmsg("murder_by_named_mob", name, hittername)
 				elseif hittersubtype ~= nil and hittersubtype ~= "" then
 					msg = mmsg(hittersubtype, name)
 				else