Correctly Warn Incorrect v-Slot Usage

# Introduction

In this project, you will learn how to fix a bug in the `vue-router 3.1.3` code where the component rendering fails when creating a router link component using the `v-slot API` and providing multiple child elements.

## 👀 Preview


## 🎯 Tasks

In this project, you will learn:

- How to locate and identify the issue in the `vue-router 3.1.3` code
- How to fix the issue by modifying the code in the `link.js` file
- How to rebuild and release the fixed `vue-router 3.1.3` project
- How to verify the fixed effect by testing the application

## 🏆 Achievements

After completing this project, you will be able to:

- Troubleshoot and fix issues in a third-party library
- Rebuild and release a project after making code changes
- Test and verify the functionality of a fixed issue