refactor repeatStr function to improve error handling and maintain structure

Author: AkliluMihtsun

practice-tdd/repeat-str.js

@@ -1,9 +1,12 @@
 export function repeatStr(word, n) {
   // 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.
-  let nWords = "";
-  for (let i = 0; i < n; i++) {
-    nWords = nWords + word;
+  if (n >= 0) {
+    let nWords = "";
+    for (let i = 0; i < n; i++) {
+      nWords = nWords + word;
+    }
+    return nWords;
   }
-  return nWords;
+  throw new Error("Error");
 }