https://invent.kde.org/frameworks/kio/-/commit/48322f44323a1fc09305d66d9093fe6c3780709e
Index: src/ioslaves/file/file_unix.cpp
--- src/ioslaves/file/file_unix.cpp.orig
+++ src/ioslaves/file/file_unix.cpp
@@ -328,6 +328,9 @@ inline static time_t stat_mtime(const QT_STATBUF &buf)
 static bool isOnCifsMount(const QString &filePath)
 {
     const auto mount = KMountPoint::currentMountPoints().findByPath(filePath);
+    if (!mount) {
+        return false;
+    }
     return mount->mountType() == QStringLiteral("cifs") || mount->mountType() == QStringLiteral("smb3");
 }
 
