updated answer in errors 3.js

Author: TzeMingHo

Sprint-1/2-mandatory-errors/3.js

@@ -1,5 +1,5 @@
-const cardNumber = '4533787178994213';
-const last4Digits = cardNumber.slice(-4);
+const cardNumber = 4533787178994213;
+const last4Digits = String(cardNumber).slice(-4);
 
 // A number was not able to be sliced, whereas a string can be sliced
 // So, the error is that cardNumber should be a string, not a number