fixes up LuceneIndexDiagnostics

src/Umbraco.Examine/LuceneIndexDiagnostics.cs

@@ -4,6 +4,7 @@ using Umbraco.Core;
 using Umbraco.Core.Logging;
 using Lucene.Net.Store;
 using Umbraco.Core.IO;
+using System.Linq;
 
 namespace Umbraco.Examine
 {
@@ -60,17 +61,19 @@ namespace Umbraco.Examine
         {
             get
             {
+                var luceneDir = Index.GetLuceneDirectory();
                 var d = new Dictionary<string, object>
                 {
                     [nameof(UmbracoExamineIndex.CommitCount)] = Index.CommitCount,
                     [nameof(UmbracoExamineIndex.DefaultAnalyzer)] = Index.DefaultAnalyzer.GetType().Name,
-                    ["LuceneDirectory"] = Index.GetLuceneDirectory().GetType().Name,
-                    [nameof(UmbracoExamineIndex.LuceneIndexFolder)] =
-                        Index.LuceneIndexFolder == null
-                            ? string.Empty
-                            : Index.LuceneIndexFolder.ToString().ToLowerInvariant().TrimStart(IOHelper.MapPath(SystemDirectories.Root).ToLowerInvariant()).Replace("\\", "/").EnsureStartsWith('/'),
+                    ["LuceneDirectory"] = luceneDir.GetType().Name                    
                 };
 
+                if (luceneDir is FSDirectory fsDir)
+                {
+                    d[nameof(UmbracoExamineIndex.LuceneIndexFolder)] = fsDir.Directory.ToString().ToLowerInvariant().TrimStart(IOHelper.MapPath(SystemDirectories.Root).ToLowerInvariant()).Replace("\\", "/").EnsureStartsWith('/');
+                }
+
                 return d;
             }
         }