extendMarkdownIt not work

It is indeed called when debugging, but it has no effect
```
// extendMarkdownIt.ts
export default function (md: any) {
    md.options.replaceLink = (link: string, env: any) => {
       return './1.png'
    };
    return md.use(require("markdown-it-replace-link"));
}
```

my markdown file
```
![](./2.png)
```
