I can still reproduce, the warning is a little more usable with Java 17:
2023-12-07 16:08:04,208 [qtp1297149880-250 - http://127.0.0.1:8080/xwiki/bin/download/XWiki/DefaultSkin/filename] WARN c.x.x.p.XWikiPluginManager - downloadAttachment failed for plugin [image]: Cannot invoke "com.xpn.xwiki.doc.XWikiAttachment.getMimeType(com.xpn.xwiki.XWikiContext)" because "attachment" is null 2023-12-07 16:08:04,208 [qtp1297149880-250 - http://127.0.0.1:8080/xwiki/bin/download/XWiki/DefaultSkin/filename] WARN c.x.x.p.XWikiPluginManager - downloadAttachment failed for plugin [zipexplorer]: Cannot invoke "com.xpn.xwiki.doc.XWikiAttachment.getReference()" because "attachment" is null