add missing import

lib/pipeline/webpackProcess.js

@@ -4,6 +4,7 @@ const utils = require('../utils/utils');
 const fs = require('../core/fs');
 const constants = require('../constants');
 const HardSourceWebpackPlugin = require('hard-source-webpack-plugin');
+const ProcessWrapper = require('../processes/processWrapper');
 const path = require('path');
 
 let webpackProcess;