FIXES #4171 pen args mismatched inside note blocks (#4175)

* Update logo.js

Declaring `arg` within the function to avoid sharing state.

* Update logo.js

no need of comment there.

Author: omsuneri

js/logo.js

@@ -1843,8 +1843,8 @@ class Logo {
 
         const suppressOutput = tur.singer.suppressOutput;
 
-        let arg;
         const __pen = (turtle, name, b, timeout) => {
+            let arg;
             switch (name) {
                 case "penup":
                 case "pendown":