fixing code based on mentor feedback

Author: Abduhasen

Sprint-3/2-practice-tdd/repeat-str.js

@@ -1,13 +1,15 @@
 function repeatStr(str, num) {
-  let result = "";
   // Your implementation of this function must *not* call String.prototype.repeat (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/repeat).
   // The goal is to re-implement that function, not to use it.
-
   if (num < 0) {
     throw new Error();
   }
+  let result = "";
+  for (let i = 0; i < num; i++) {
+    result += str;
+  }
 
-  return str.repeat(num);
+  return result;
 }
 
 module.exports = repeatStr;