old_contents: var through = require('through2'),
      gutil = require('gulp-util'),
      rasterize = require('./lib'),
      PluginError = gutil.PluginError;
  
  const PLUGIN_NAME = 'gulp-raster';
  
  module.exports = function (opt) {
      'use strict';
  
      opt = opt || {};
      opt.scale = opt.scale || 1;
      opt.format = opt.format || 'png';
  
      function raster(file, enc, callback) {
          var that = this;
  
          // Do nothing if no contents
          if (file.isNull()) { return callback(); }
  
          if (file.isBuffer()) {
              rasterize(file.path, opt.format, opt.scale, function (err, data) {
                  if (err) { throw new PluginError(PLUGIN_NAME, 'Error occured during file convertation'); }
  
                  file.contents = data;
                  that.push(file);
                  return callback();
              });
          }
      }
  
      return through.obj(raster);
  };
  
new_contents: var through = require('through2'),
      gutil = require('gulp-util'),
      rasterize = require('./lib'),
      PluginError = gutil.PluginError;
  
  const PLUGIN_NAME = 'gulp-raster';
  
  module.exports = function (opt) {
      'use strict';
  
      opt = opt || {};
      opt.scale = opt.scale || 1;
      opt.format = opt.format || 'png';
  
      function raster(file, enc, callback) {
          var that = this;
  
          // Do nothing if no contents
          if (file.isNull()) { return callback(); }
  
          if (file.isBuffer()) {
              rasterize(file.path, opt.format, opt.scale, function (err, data) {
                  if (err) { throw new PluginError(PLUGIN_NAME, 'Error occured during file conversion'); }
  
                  file.contents = data;
                  that.push(file);
                  return callback();
              });
          }
      }
  
      return through.obj(raster);
  };
  
subject: fix typo