Be resilient to VS API version changes in navigateto.

src/EditorFeatures/Core/Implementation/NavigateTo/NavigateToItemProvider.cs

@@ -59,10 +59,7 @@ public void StartSearch(INavigateToCallback callback, string searchValue)
                 return;
             }
 
-            var optionsService = _optionsServices.Length > 0
-                ? VersionSelector.SelectHighest(_optionsServices)
-                : null;
-            var searchCurrentDocument = optionsService?.GetSearchCurrentDocument(callback.Options) ?? false;
+            var searchCurrentDocument = GetSearchCurrentDocumentOption(callback);
             var searcher = new Searcher(
                 _workspace.CurrentSolution,
                 _asyncListener,
@@ -74,5 +71,30 @@ public void StartSearch(INavigateToCallback callback, string searchValue)
 
             searcher.Search();
         }
+
+        private bool GetSearchCurrentDocumentOption(INavigateToCallback callback)
+        {
+            try
+            {
+                return GetSearchCurrentDocumentOptionWorker(callback);
+            }
+            catch (TypeLoadException)
+            {
+                // The version of the APIs we call in VS may not match what the 
+                // user currently has on the box (as the APIs have changed during
+                // the VS15 timeframe.  Be resilient to this happening and just
+                // default to searching all documents.
+                return false;
+            }
+        }
+
+        private bool GetSearchCurrentDocumentOptionWorker(INavigateToCallback callback)
+        {
+            var optionsService = _optionsServices.Length > 0
+                ? VersionSelector.SelectHighest(_optionsServices)
+                : null;
+            var searchCurrentDocument = optionsService?.GetSearchCurrentDocument(callback.Options) ?? false;
+            return searchCurrentDocument;
+        }
     }
 }