Fix the Test in async.spec.js

# Introduction

In this project, you will learn how to fix an issue in the `async.spec.js` file within the `vue-router-3.0.1` project. The `async.spec.js` file contains a test case that is not correctly detecting an error, and your task is to modify the code to ensure the test passes as expected.

## 👀 Preview

Message:
    Expected $.length = 3 to equal 5.
    Expected $[3] = undefined to equal 4.
    Expected $[4] = undefined to equal 5.

## 🎯 Tasks

In this project, you will learn:

- How to locate and modify the `async.spec.js` file in the `vue-router-3.0.1` project
- How to understand the issue with the existing test case
- How to implement the necessary changes to fix the test case

## 🏆 Achievements

After completing this project, you will be able to:

- Identify and fix issues in unit tests
- Work with asynchronous code and the `runQueue` utility function
- Apply techniques for debugging and troubleshooting test cases