minor fixes

1-js/04-object-basics/07-optional-chaining/article.md

@@ -173,18 +173,16 @@ Then `?.()` checks the left part: if the admin function exists, then it runs (th
 The `?.[]` syntax also works, if we'd like to use brackets `[]` to access properties instead of dot `.`. Similar to previous cases, it allows to safely read a property from an object that may not exist.
 
 ```js run
+let key = "firstName";
+
 let user1 = {
   firstName: "John"
 };
 
-let user2 = null; // Imagine, we couldn't authorize the user
-
-let key = "firstName";
+let user2 = null; 
 
 alert( user1?.[key] ); // John
 alert( user2?.[key] ); // undefined
-
-alert( user1?.[key]?.something?.not?.existing); // undefined
 ```
 
 Also we can use `?.` with `delete`: