anchor.diff:            }
             break;
         }
  +    }).catchError((e, st) {
  +      print('Exception in AnalysisDomainHandler.getNavigation()');
  +      print(e);
  +      print(st);
       });
       // delay response
       return Response.DELAYED_RESPONSE;
  
positive.code:           }
            break;
          case AnalysisDoneReason.CONTEXT_REMOVED:
            // The active contexts have changed, so try again.
            Response response = getNavigation(request);
            if (response != Response.DELAYED_RESPONSE) {
  
negative.code:     analysisFuture.then((AnalysisDoneReason reason) {
        switch (reason) {
          case AnalysisDoneReason.COMPLETE:
            print('AnalysisDoneReason.COMPLETE');
            List<CompilationUnit> units =
                server.getResolvedCompilationUnits(file);
            print('units: $units');
            if (units.isEmpty) {
              server.sendResponse(new Response.getNavigationInvalidFile(request));
            } else {
  