anchor.diff:    }
   
     Future<int> printVersion() async {
  +    if (executor.persistentStore == null) {
  +      print("No database to connect to. Provide a dbconfig file in migrations/migration.yaml in the following format $_dbConfigFormat");
  +      return -1;
  +    }
       try {
         var current = await executor.persistentStore.schemaVersion;
         print("Current version: $current");
  
positive.code: 
  
    Future cleanup() async {
      await executor.persistentStore.close();
    }
  
  
    String _getPackageName(Uri projectURI) {
      var yamlContents = new File.fromUri(projectURI.resolve("pubspec.yaml")).readAsStringSync();
  
negative.code: part of aqueduct;
  
  class MigrationRunner extends CLICommand {
    MigrationExecutor executor;
  