Fix typo in 1.4.7 (optional chaining)

Author: vsemozhetbyt

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

@@ -56,7 +56,7 @@ let user = {}; // user has no address
 alert(user.address ? user.address.street ? user.address.street.name : null : null);
 ```
 
-That's just awful, one may even problems understanding such code. 
+That's just awful, one may even have problems understanding such code. 
 
 Don't even care to, as there's a better way to write it, using the `&&` operator: