How to prevent trailing slash being added to the paths in additionalPaths

Describe the bug A trailing slash is being added to the paths in additionalPaths. I previously created a bug report but it was closed, assuming it was fixed, I tried with the latest version but still experience the same behaviour so recreating the issue again.

To Reproduce Steps to reproduce the behavior:

1. Update next-sitemap.js:

module.exports = {
  siteUrl: 'https://example.com',
  generateRobotsTxt: true,
  additionalPaths: async (config) => [
    await config.transform(config, '/additional-page.html'),
  ],
};

1. Build and export next app
2. Result:

<url><loc>https://example.com/additional-page.html/</loc><changefreq>daily</changefreq><priority>0.7</priority><lastmod>2021-10-15T07:05:21.440Z</lastmod></url>

Expected behavior It shouldn’t include trailing slash if not needed - <loc>https://example.com/additional-page.html</loc>. When crawlers access the page with trailing slash (e.g. https://example.com/additional-page.html/), the page will break because of the assets it requires. It should be accessed by crawlers without the trailing slash.

Additional context I’m using next-sitemap@1.8.4.

[iamvishnusankar]

@dominicarrojado @mordgard Fixed #310

[dominicarrojado]

@iamvishnusankar I’m afraid it is still not fixed: https://codesandbox.io/s/interesting-tu-toztvx?file=/next.config.js

When there’s next.config.js with the trailingSlash: true. the next-sitemap.js config does not override it.