old_contents: //electron entry-point
  
  const REACT_DEVELOPER_TOOLS = require('electron-devtools-installer').REACT_DEVELOPER_TOOLS;
  var installExtension = require('electron-devtools-installer').default;
  var app = require('electron').app;
  var BrowserWindow = require('electron').BrowserWindow;
  var path = require( "path" );
  
  if (process.env.NODE_ENV === 'development') {
    require('electron-debug')(); // eslint-disable-line global-require
  }
  
  app.on('ready',function() {
  
  installExtension(REACT_DEVELOPER_TOOLS)
    .then((name) => console.log(`Added Extension:  ${name}`))
    .catch((err) => console.log('An error occurred: ', err));
  
    var mainWindow = new BrowserWindow({
      width: 1200,
      height: 600
    });
    mainWindow.loadURL('file://' + __dirname + '/src/index-electron.html');
  
    mainWindow.webContents.on('did-finish-load', () => {
      mainWindow.show();
      mainWindow.focus();
    });
  
    mainWindow.on('closed', () => {
      mainWindow = null;
    });
  
    if (process.env.NODE_ENV === 'development') {
      mainWindow.openDevTools();
    }
  
  });
  
new_contents: //electron entry-point
  var app = require('electron').app;
  var BrowserWindow = require('electron').BrowserWindow;
  var path = require( "path" );
  
  if (process.env.NODE_ENV === 'development') {
    require('electron-debug')(); // eslint-disable-line global-require
  }
  
  app.on('ready',function() {
  
  if(process.env.NODE_ENV === 'development') {
    const REACT_DEVELOPER_TOOLS = require('electron-devtools-installer').REACT_DEVELOPER_TOOLS;
    var installExtension = require('electron-devtools-installer').default;
    installExtension(REACT_DEVELOPER_TOOLS)
    .then((name) => console.log(`Added Extension:  ${name}`))
    .catch((err) => console.log('An error occurred: ', err));
  }
  
    var mainWindow = new BrowserWindow({
      width: 1200,
      height: 600
    });
    mainWindow.loadURL('file://' + __dirname + '/src/index-electron.html');
  
    mainWindow.webContents.on('did-finish-load', () => {
      mainWindow.show();
      mainWindow.focus();
    });
  
    mainWindow.on('closed', () => {
      mainWindow = null;
    });
  
    if (process.env.NODE_ENV === 'development') {
      mainWindow.openDevTools();
    }
  
  });
  
subject: Load react-devtools in dev env only