Fix the XML sitemap generation with present, but NOT installed modules
Created by: tinogo
Currently, it is not possible to generate the XML sitemaps, when a certain module is present in the filesystem but which is not installed.
Steps to repeat:
- Add the news module (or any other module which registers a XML sitemap extension) via composer
- Do NOT install the module
- Try to generate the XML sitemap via the SEO module
Actual result: The XML sitemap generation dies with an exception.
Expected result: The XML sitemap is being generated flawlessly.