It’s strange, sounds like a bug but would need to find the way to reproduce it. Would be great if you could create a BUG issue on Loading... with everything you remember about what happen related to Latex Exporter (index when 1.25.1 did not exist, install 1.25, 1.25.1 was released, installed other things in between, etc.).
In the meantime, you can probably “fix” this that deleting the index and let XWiki recreate it from scratch. For that, you will need to:
- stop XWiki
- delete the
<permdir>/cache/solr/extension_index_9(or<permdir>/cache/solr/extension_indexfor older versions of XWiki) - start XWiki