In repeat-str.js now first testing if number is 0 already

Author: hoimir

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

@@ -2,6 +2,9 @@ function repeatStr(str, count) {
   if (count < 0) {
     throw new Error("Negative counts are not valid");
   }
+  if (count === 0) {
+    return "";
+  }
   let result = "";
   for (let i = 0; i < count; i++) {
     result += str;