remove nan values from digiline messages

tubes/lua.lua

@@ -370,7 +370,10 @@ local function clean_and_weigh_digiline_message(msg, back_references)
 		return msg, #msg + 25
 	elseif t == "number" then
 		-- Numbers are passed by value so need not be touched, and cost 8 bytes
-		-- as all numbers in Lua are doubles.
+		-- as all numbers in Lua are doubles. NaN values are removed.
+		if msg ~= msg then
+			return nil, 0
+		end
 		return msg, 8
 	elseif t == "boolean" then
 		-- Booleans are passed by value so need not be touched, and cost 1