anchor.diff:            try {
               final resolvedUnitResult =
                   await context.currentSession.getResolvedUnit(filePath);
  +
  +            var error = _getFirstErrorOrNull(resolvedUnitResult);
  +            if (error != null) {
  +              print('File $filePath skipped due to errors such as:');
  +              print('  ${error.toString()}');
  +              print('');
  +              continue;
  +            }
  +
  +            // Use the ExpectedCompletionsVisitor to compute the set of expected
  +            // completions for this CompilationUnit.
               final visitor = ExpectedCompletionsVisitor();
  -
               resolvedUnitResult.unit.accept(visitor);
   
               for (var expectedCompletion in visitor.expectedCompletions) {
  
positive.code:     mRRComputer.clear();
    }
  
    Future<List<CompletionSuggestion>> _computeCompletionSuggestions(
        ResolvedUnitResult resolvedUnitResult, int offset,
        [DeclarationsTracker declarationsTracker]) async {
  
negative.code: import 'package:analysis_server/src/status/pages.dart';
  import 'package:analyzer/dart/analysis/analysis_context_collection.dart';
  import 'package:analyzer/dart/analysis/results.dart';
  import 'package:analyzer/diagnostic/diagnostic.dart';
  import 'package:analyzer/error/error.dart' as err;
  import 'package:analyzer/file_system/physical_file_system.dart';
  import 'package:analyzer/src/dart/analysis/byte_store.dart';
  import 'package:analyzer/src/generated/engine.dart';
  