DYN-8941: dont crash when theres no cluster results (#16264)

Co-authored-by: john pierson <sixtysecondrevit@gmail.com>

Author: chubakueno

src/NodeAutoCompleteViewExtension/ViewModels/NodeAutoCompleteBarViewModel.cs

@@ -1032,10 +1032,12 @@ internal void PopulateAutoComplete()
                     }
                     // this runs synchronously on the UI thread, so the UI can't disappear during execution
                     DropdownResults = comboboxResults;
-                    SelectedIndex = 0;
-
-                    var ClusterResultItem = QualifiedResults.First();
-                    AddCluster(ClusterResultItem);
+                    if (comboboxResults.Any())
+                    {
+                        SelectedIndex = 0;
+                        var ClusterResultItem = QualifiedResults.First();
+                        AddCluster(ClusterResultItem);
+                    }
 
                 });
             });