Update Jellyfin.Server/Middleware/UrlDecodeQueryFeature.cs

Co-authored-by: Claus Vium <cvium@users.noreply.github.com>

Jellyfin.Server/Middleware/UrlDecodeQueryFeature.cs

@@ -46,7 +46,7 @@ namespace Jellyfin.Server.Middleware
 
                 // Encoded querystrings have no value, so don't process anything if a value is present.
                 var (key, stringValues) = value.First();
-                if (!string.IsNullOrEmpty(kvp.Value))
+                if (!string.IsNullOrEmpty(stringValues))
                 {
                     _store = value;
                     return;