fix: update tally function to create empty object and add test for inherited properties

Author: jakr-s

Sprint-2/implement/tally.js

@@ -3,7 +3,7 @@ function tally(arr) {
     throw new Error();
   }
 
-  let result = {};
+  let result = Object.create(null);
 
   for (const element of arr) {
     if (element in result) {

Sprint-2/implement/tally.test.js

@@ -20,4 +20,9 @@ describe("tally", () => {
     expect(() => tally(null)).toThrow();
     expect(() => tally(undefined)).toThrow();
   });
+
+  test("tally returns an object with no inherited properties", () => {
+    const result = tally(["a", "b", "a"]);
+    expect(Object.getPrototypeOf(result)).toBeNull();
+  });
 });