[array.head]: simplify returning of first element

src/array/head.js

@@ -7,9 +7,7 @@ import checkArray from "./_checkArray";
  */
 const head = (ar) => {
     checkArray(ar);
-
-    const [head, ...rest] = ar;
-    return head;
+    return ar[0];
 };
 
 export default head;