anchor.diff:      var newLine = (escapeLabels) ? r'\n' : '\n';
   
       var label = name;
  -    if (version.isNotEmpty) {
  +    if (version != null) {
         label = label + '$newLine$version';
       }
   
  
positive.code:       String packageName = pubspecMap['name'];
        assert(packageName != null && packageName.length > 0);
  
        String version = pubspecMap['version'];
        if (version == null) version = '';
  
        var deps = Dependency.getDependencies(pubspecMap);
  
  
negative.code: import 'package:yaml/yaml.dart' as yaml;
  
  import 'dependency.dart';
  import 'version.dart';
  
  class VizPackage extends Comparable {
    final String path;
    final String name;
    final Version version;
    final Set<Dependency> dependencies;
    bool isPrimary = false;
  
  