fixed eslint error & integrated with prettier as well as formatted the whole codebase (#3450)

lib/main-app.js

@@ -36,8 +36,9 @@ const updater = new GhReleases(ghReleasesOpts)
 
 // Check for updates
 // `status` returns true if there is a new update available
-function checkUpdate () {
-  if (!isPackaged) { // Prevents app from attempting to update when in dev mode.
+function checkUpdate() {
+  if (!isPackaged) {
+    // Prevents app from attempting to update when in dev mode.
     console.log('Updates are disabled in Development mode, see main-app.js')
     return true
   }
@@ -58,29 +59,29 @@ function checkUpdate () {
   })
 }
 
-updater.on('update-downloaded', (info) => {
+updater.on('update-downloaded', info => {
   if (mainWindow != null) {
     mainWindow.webContents.send('update-ready', 'Update available!')
     isUpdateReady = true
   }
 })
 
-updater.autoUpdater.on('error', (err) => {
+updater.autoUpdater.on('error', err => {
   console.error(err)
 })
 
-ipc.on('update-app-confirm', function (event, msg) {
+ipc.on('update-app-confirm', function(event, msg) {
   if (isUpdateReady) {
     mainWindow.removeAllListeners()
     updater.install()
   }
 })
 
-app.on('window-all-closed', function () {
+app.on('window-all-closed', function() {
   app.quit()
 })
 
-app.on('ready', function () {
+app.on('ready', function() {
   mainWindow = require('./main-window')
 
   var template = require('./main-menu')
@@ -100,7 +101,7 @@ app.on('ready', function () {
   }
 
   // Check update every day
-  setInterval(function () {
+  setInterval(function() {
     if (isPackaged) checkUpdate()
   }, 1000 * 60 * 60 * 24)
 
@@ -108,7 +109,7 @@ app.on('ready', function () {
   setTimeout(() => {
     if (isPackaged) checkUpdate()
 
-    ipc.on('update-check', function (event, msg) {
+    ipc.on('update-check', function(event, msg) {
       if (isUpdateReady) {
         mainWindow.webContents.send('update-ready', 'Update available!')
       } else {