Update

Author: IPRIT

src/lib/priority-queue/priority-queue.spec.ts

@@ -19,8 +19,8 @@ test('queue/dequeue', t => {
   t.deepEqual(queue.dequeue(), { id: 3 });
   t.deepEqual(queue.dequeue(), { id: 1 });
 
-  t.deepEqual(queue.peek(), null);
-  t.deepEqual(queue.dequeue(), null);
+  t.deepEqual(queue.peek(), undefined);
+  t.deepEqual(queue.dequeue(), undefined);
 });
 
 test('size', t => {

src/lib/priority-queue/priority-queue.ts

@@ -2,7 +2,7 @@ import { MaxHeapTree } from '@algo-js/heap-tree';
 
 export interface Queue<T> {
   queue: (item: T, priority: number) => this;
-  dequeue: () => T;
+  dequeue: () => T | undefined;
 
   readonly size: number;
 }
@@ -87,7 +87,7 @@ export class PriorityQueue<T> extends MaxHeapTree<T> implements Queue<T> {
    * @private
    * @deprecated
    */
-  public poll(): T {
+  public poll(): T | undefined {
     throw new Error('Use `dequeue` method instead');
   }
 }