code: function rpt_cb (err, data) {
      if (err) return logger.error(err)
      if (data.error) return logger.error(data.error)
      if (!data.package) {
        logger.warn('`data.package` not defined. Initializing placeholder.')
        data.package = {}
      }
  
      var dependencyReport = {}
  
      if (!data.package || !data.package.name) logger.warn('`data.package.name` missing')
      dependencyReport.name = data.package.name
  
      if (!data.package || !data.package.version) logger.warn('`data.package.version` missing')
      dependencyReport.version = data.package.version
  
      if (options.meta) {
        dependencyReport.meta = {
          nodeVersions: process.versions,
          date: Date.now()
        }
      }
  
      buildDependencyReport(dependencyReport, data, options, 0)
  
      // Finally, return gatherDependencies callback
      callback(null, dependencyReport)
    }
docs: read-package-tree callback
  @param  {error}  err  read-package-tree error
  @param  {object} data read-package-tree blob (contains cyclical refrences)